Imo it's one thing for people to say they will leave/divorce a cheater but you never truly know how you'll feel/react until the situation happens in real life. It's alright if you want to keep your family together and are prepared to forgive if she feels remorse and wants to reconcile, but if a PA truly is a boundary for you you have to be prepared to enforce it, and you're very likely already in a situation with a PA. Sorry to say that, because I know it hurts, but better to face reality than ignore it.
My situation is a bit unique in that she is in an EA right now, even though it was PA before BD. It was the PA that led her to BD in the first place - I am 100% sure; The promise of a new life is a powerful motivation for D. I decided to LRT/GAL/180 after that and I am still in that journey. But I am keen on setting boundaries. I know that it will become PA again if she travels to where OM lives. And in my current disposition that becomes a deal breaker. I am mentally preparing myself for that action even though saving the MR is the north star.