"You're going to have to pick yourself up now. Ultimatums given in a kind loving way describing a boundary for you is attractive and masculine. Giving an ultimatum and then apologizing for making her choose is not."
Love this, Inside ^^^^^.
The most important things about a boundary are - that the intent is not to punish or shame the other person, that it is set as a way to protect you and that once it is set, it needs to be followed through on.
So, you said you cannot work on the marriage with her while she is with OM. That means, no sleeping together, no conversations about your relationship, right?