Just caught up on your sitch- I'm in the same boat but w/o kids...EVERYTHING you say goes for me- no communication, no opportunity to make things better- no chance.
Def do what you need to protect yourself- she is obv out for herself and will take out her feelings of guilt as anger on you.
Keep working on yourself, forget about OM- she's using him to feel better, while you're busy working on yourself and being a man of integrity.
