Is it a sin of detraction to reveal faults of the parents if they're abusive so that people know what's going on, especially when asked? I've been trying to practice christian virtues to forgive and tolerate my parent and every time I told people about what my parent did to me (constant insult and shaming in front of everyone etc.) I worried that I sinned. Also will it be against church teaching to cut off parents if they're abusive? Or how abusive do they have to be to become grounds for cutting them off?

The best advice is obviously discussing it with a good priest.

To be able to say something here, it would be interesting to know your age, your gender, if you live with your parents or not.

Based just on what you said on the opening post, what would be the point of exposing your parents abuse towards you to other people? Venting? Solace? Just that?

The abuse is only verbal?

And also I didn't ask a priest because 1. I don't have a priest that I trust and 2. I don't know if discussing this with a priest will be a detraction since that way he'll know what they did

There has to be some legitimate reason for disclosing the faults of anyone.  There's probably an additional component with regard to the 4th Commandment to Honor your Mother or Father.

So it would partly depend on whether you had legitimate reason for disclosing these faults.  Legitimate reason might include the need to discuss it with someone because of the psychological / emotional harm it caused you, perhaps to get feedback and advice from others, or even, if this abuse took place in public, to restore the damage done to your reputation.

So, if the faults revealed were grave sins, then the detraction would be a grave sin ... unless you had a relatively-grave reason to reveal them.  If the faults were not grave sins, then the detraction would also not be grave, and may not be a sin of detraction at all if you have a much less weighty reason to reveal them.

To me, if you were seeking counsel, advice, or just wanted to confide in a close friend (who could help you deal with it or give some good advice), then that sounds like legitimate reason to discuss the faults.

Also, since you mentioned that the humiliation / abuse took place in public, those who saw it in public or are in a close enough circle with those who saw it in public (and would likely be in a position to know/hear about it), there would be no detraction in speaking to those about it.  In fact, your reputation may have been damaged in front of people such as these, and you have a right to repair the damage.

So, between the fact that they abused/humiliated you in public, and you have the right to restore your own reputation, in my opinion, so long as you're not going around revealing the fault for no reason (i.e. just to get revenge by ruining their reputation), my guess is that there's no sin there.

Yet, "just verbal". There's so much emotional abuse and manipulation to a point that every time I spoke to my parent I felt like I want to kill myself.

If this is damaging you badly enough to make you feel as though you wanted to kill yourself, then talking about it to someone to help with that damage is perfectly legitimate.  Basically, there would be sin there if you're going around indiscriminately telling people for no reason, just to gossip.  If you have a legitimate reason, such as helping to alleviate the stress / depression it has caused, to seek advice, or even to undo some harm your parents caused you by doing this in public.  IMO, all those would be legitimate reasons to talk about it with others ... just not to spread idle gossip or out of revenge ("they ruined my reputation, so I'm going to ruin theirs").  Those latter would not be legitimate and would render it sinful.  But to talk about it with a close friend or two to help you deal with the damage it's caused you or to help restore your reputation that may have been damaged by their abuse ... those would be legitimate reasons to speak about it.  If you do speak to close friends to help you cope, you should ask them to keep it between you and not spread it around.

Female in mid 20s. I don't live with them but a parent is trying to force me to live together again so that I can share rent. There would be scenarios that I got asked why I don't want to live with them or why we don't talk and I didn't know how to answer because I think even a simple answer as "he/she treats me badly" was a form of detraction.
Yet, "just verbal". There's so much emotional abuse and manipulation to a point that every time I spoke to my parent I felt like I want to kill myself.

I know you didn't ask for it, but I'll offer some advice, if I may.

Based on what you say, I think that it is reasonable to imagine that you grew up in an abusive enviroment. Your parents probably have treated you as an incompetent and lesser person, when you know that you are not. They have manipulated you to suit their needs and desires.

I would advise against going back to live with them. You could give them some money to help with rent, although you are not obliged to do that, unless they are very poor or in bad health.

When people ask, you can always give evasive answers. You could simply say that you think it is better if you live apart. You can say that you were not getting along very well, without giving any details, or you can simply pretend that you don't understand the question and talk about something else. Evasive answers are not sinful, and are often our only possible answers, if we don't want to sin by lying.

If they have been abusive and manipulative all your life, chances are they won't change now. Even if you try to set boundaries, they will probably respond with even more manipulation and aggression.

If you live near them, you could spend an hour or two with them every fortnight, if you can handle it. If not, go once a month and stay one hour. If you live far from them, you may go once a year or every six months and spend a day or two. You might even stay in a hotel in these occasions.

I believe that the key is to try to stay on friendly terms and visit them once in a while, as long as it is something that you can handle and that won't be a great harm to you. Only you know how much is too much. Cutting them off completely would be the last option.

I believe that Ladislaus gave a very balanced opinion about detraction. I have nothing to add.

I don't think that cutting them off would be a sin, if they are absolutely unbearable.

Even if you don't have a priest in whom you trust completely, talk about it with any reasonably good traditional priest during confession. You are not obliged to do what he says, but it might be good for you to listen to advice from a qualified person. You can do this with different priests. Their advices might be complementary to each other.

Is it a sin of detraction to reveal faults of the parents if they're abusive

First of all, are you being objective?  emotional?  Is the so called abuse because of their frustration with your behaviour?  The shaming in front of other people  ... were you actually guilty of what you were being accused?

70-80 years ago parents followed "don't spare the rod" .  This extended to verbal also (but that usually only meant once or twice) but after that a stern look was usually sufficient.

Do you think your parents are behaving a certain way just to be mean?  That's an important question.

If you're in your mid 20's, you just came out of the trying teens.  You may think you were an angel but how did you respond to their "abuse"...were you silent and submissive or did you respond in kind?  Did you rebel?   

Today the word "abuse" is thrown around for every little thing that hurts our little feelings.

I'm not trying to judge you, but you should judge yourself.  You may be justified in your feelings on all counts, some counts, or no counts.  Only you can decide.

To be truly Catholic, follow the example of the saints (and there are many).  When falsely accused they kept silent and let their behaviour speak for itself. (and they probably offered it up).

You may feel you have the "right"  to clear your name (as Lad says) but is it truly going to resolve the situation or make it worse?

From my personal experience:

Experienced all 4 types of abuse as a kid.  I became a Christian as an adult so didn't know what detraction was (thanks Ignis Ardens).  When my children reached the age of reason I had to reveal some of my parents abuse of me so that they could understand my perspective and why I had nothing to do with them.  My father passed at the time I became a traditional Catholic, but Mom lived for another decade.  In that time, she mocked my faith (she was not Catholic), made blasphemous statements about the Eucharist, and openly spoke of New Age and occultism TO MY CHILDREN.  I finally went no contact and 5 priests all gave the same instruction--have nothing to do with her unless she needed financial or physical support.  I had no communication with her but the last year of her life I began sending her money.  She died without ever making amends or even telling me she was ill.  But she cashed my checks. 

This sounds almost exactly like my future situation. I will certainly NOT want my parents near my children in the future just because of potential poison they may feed to them.