Laudislaus has given some very good advice here and brought up many good points...

I personally know two traditional Catholic families who went through a "legal divorce" and I also have a friend whose sister went through one.  Of the ones I know person, one family had 12 children, the other had 10 children.  Of my friends sister, she had 4-7 children (I can't remember the exact number but they were still quite young when it happened I believe). 

In EVERY case the excuse was to divorce the traditional Catholic spouse because the other one was tired of them.  In EVERY case the mother was given custody of the children even when the mother was the instigator of the divorce.  In EVERY case the children suffered terribly.

In the two cases where I know the families personally, the mothers were the instigators.  Their "excuses" for the divorces we're that their husbands were abusive but even though their husbands may have been choleric in nature, I don't think they were really abusive to any sort of degree to justify a divorce.  In reality it was an excuse for the wives to "get away" and take any of the minor aged children with them.  They then (in both cases) sent their children to treatments to have them learn to hate their fathers and tried as much as possible to keep the fathers from having any contact with the children but also making them pay support.

As for the friend's sister's case...  Her husband was the instigator.  He left the Faith and found another woman.  She was given custody of the children and went to live with her mother.  I don't know as much about what happened with her family in the end but I remember that it was a very sad and traumatic time for the family and the children when it happened.

I guess the questions for the OP is this...

Are there children involved?  Most of us are assuming so. 

Is the spouse in question abusive to the point of neglect and harm to the children?

If not, keeping the family together is of the MOST importance.  The primary purpose of marriage if you are a traditional Catholic is the begetting and raising of children.  This is the duty and obligation of a married person.  The spiritual and physical well-being of the children come first before any emotional connection or disconnection with one's spouse.  This is why marriage is until death. 

The True Church only allows "separation" for VERY intense reasons.

Yes, your experience squares exactly with mine ... where the mothers were the instigators, and they made false allegations of abuse, and as a result they got sole custody of the children, not to mention an incredibly favorable financial settlement.  Judges / courts will ALWAYS believe the woman over a man, and as soon as she alleges abuse (as OP indicates his wife already has), it's over for the man.  And, depending on the wife's mentality, i.e. whether she's a convert or otherwise not solidly a Traditional Catholic, she may even use this "cult-like Trad Catholicism" argument against the man.

Here are some of the ONLY ways a man has a chance to get custody of the children:

1) prove that the woman is a drug addict
2) if the husband were pro-jab and the wife anti-jab (use that against the woman to gain custody)
3) if the husband is an atheist and the wife a Traditional Catholic (could use the cult allegation against her)
4) medically-docuмented extreme physical abuse by the mother/wife ... to the point where the child ended up in ER or something

And here's another risk.  We have OP asserting that the wife is abusive.  And OP also states that the wife has accused him of being abusive.  Where this could go south is if the judge believes both allegations and then gets CPS involved to remove the children from both parents' custody.  That is even more likely if it's found out that both parents are Traditional Catholics.

When you divorce the message you send to future generations is when it gets tuff you can get out.  I don't envy you and I will pray for you.  Peace

While I agree in principle, my experience with women who have narcissistic personality disorder is that will absolutely and adamantly deny any suggestion that there's anything wrong with them psychologically, as narcissists absolutely cannot tolerate any suggestion of their having any kind of defect.  It's probably why it's gotten to this point in the first place.  This builds over time, where the husband (at first very gently) attempts to correct the aberrant behavior, but these corrections are met with hostility and resentment and merely end up exacerbating the situation.  Then at some point, as the behavior worsens, the husband becomes more adamant and vocal that there's something wrong with her, and there's no coming back from there for a narcissist.

I was raised by a narcissistic mother. This is so very true. My father attempted to go to therapy with her (we weren’t religious) and all she did was lie and blame all of their issues on him.

I will pray for you and your kids. You need to be their rock. She likely doesn’t give them any validation and gas lights them constantly as my mother did. Tell them the truth and form a really strong bond with them. However, be careful not to let her sense this though because she will try to destroy  your relationships with them out of pure spite if she is truly a narcissist.

I was raised by a narcissistic mother. This is so very true. My father attempted to go to therapy with her (we weren’t religious) and all she did was lie and blame all of their issues on him.

I will pray for you and your kids. You need to be their rock. She likely doesn’t give them any validation and gas lights them constantly as my mother did. Tell them the truth and form a really strong bond with them. However, be careful not to let her sense this though because she will try to destroy  your relationships with them out of pure spite if she is truly a narcissist.

Yes, that's precisely what seems to be going on here.  I didn't mean to imply that only women have NPD (narcissistic personality disorder), as I've known one man in particular who was a textbook case, but most of the ones I have happened to know were women.  And what makes it so difficult to combat is precisely the fact that the narcissism causes them to reject any and all (even constructive and gentle) attempts at correction.  At first a husband might gently attempt to correct the behavior, but those subtle attempts get nowhere, and then the husband tries to be more forceful, but then is met with hostility.  It's very difficult to cut through narcissistic personality disorder.  I'm not sure whether this is primarily a spiritual or a psychological disorder, but it's probably some blend of the two.

I'm sorry that you had to grow up with that; it's a terrible ordeal.  I know some kids who had to grow up in that kind of environment, and my wife also grew up with a mother with that disorder.  To this day, she's absolutely terrified of doing anything that might incur her mother's disapproval, even in trivial things ... even when I try to reassure her that this disapproval is completely unwarranted.  It's as if the mother set herself up as a God-like standard of all truth and reality.

My sister’s divorce was toxic.  Then she picks out a bigger loser and lives with him. She made her children call boyfriend “ daddy” She turned the two girls against their own father while making live in boyfriend daddy.  My sister even changed their last name.  Then she turned the girls against his family.  Then she turned against us.  My parents supported this sin too.  One niece is shacking up with her boyfriend and my father has no problem with it.  After many years my sister recently said that my brother in law was physically abusive. Sad terrible lies about other family members too. Miserable and diabolical.  It does mess the children up.  

It’s the devil doing havoc on the family. It is just like our Lady of Fatima warned about the destruction of family.

I'm not sure whether this is primarily a spiritual or a psychological disorder, but it's probably some blend of the two.

I’ve often wondered this myself. Unfortunately there is very little Catholic literature on the subject I have found (this is pretty interesting). Maybe because it seems to be more prevalent in our modern times than in the past? Perhaps due to the lack of true masses? I’ve talked to a priest about it but he clearly had no experience with a true narcissist because he labeled it as simple selfishness and that I should pray to her guardian angel. Not bad advice, but it’s more than simple selfishness. These people can be and often are completely evil. Almost as if they have no conscience at all. 

Out of chivalry (even if undeserved) towards my wife who has chosen invalid and illicit concubinage, and towards my son and his grandparents who are innocent in all of this, I am going to stay out of this discussion, but I just want to say this:

Don't do it.  Do anything you have to, to save your marriage.  If your spouse is the bad actor, make them change.  Force them to account to third parties for their behavior. 

Beyond that, I cannot go there. 

And for God's sake, select your spouse carefully, and if things aren't quite right before the wedding, just walk away.  I'm glad I didn't, otherwise my son wouldn't be here --- that is the saving grace in all of this, it makes everything worth it regardless --- but let me say it again, just walk away.

Wow. This was powerful and eloquent. This is by far the best post in this thread.

Another way of saying it --

There are worse things than finding yourself single at age 55.

A bad marriage is much, much worse than no marriage.

If you had to choose between "no shelter" and "residence in a Soviet gulag" which would you choose? I'd choose the torture-free, slavery-free, sleep under the stars option. Better a cardboard box in peace, than a nice concrete prison to be tortured in.