If one's spouse commits adultery, the victim spouse has two choices
B) do not forgive, and separate
If the victim spouse is going to go with Plan B, it must be done right away. You can't act like you've forgiven him/her, and then next week decide to not forgive.
But regardless of choosing A) or B) both spouses are stuck with each other for life -- even if they choose to separate.
You should ask a priest for specifics.
I do know that "adultery" is one of the few reasons a spouse can refuse the marriage debt -- and in the case of adultery, it can be indefinite.
I think it's very wise for the Church to make this allowance for human nature. For one thing, it will make that wandering spouse stop and think. Who knows, maybe he'll start thinking with the head on top of his shoulders, at least enough to hold him back.
Adultery is really stupid to begin with -- risking a stable relationship you've established, a family you've started, the lives of your children -- and for what? Usually marrying that new person isn't an option (past, present or future).
Especially for a Catholic, whose church forbids re-marriage while a spouse is still living. And if you kill your spouse, that's an impediment for a future marriage -- one that can't be given a dispensation by the Church.
And the "experience" can't vary that much... Once I was on a non-Catholic website where a bunch of guys were talking about marriage and infidelity, and several guys pointed this out. They may have been non-Catholic, but they have a point.
Going through a family break-up, divorce proceedings, living alone, etc. because you wanted to drink a glass of water from your neighbor's kitchen sink instead of your own? How stupid is that? It's water, darn it.