I hear you regarding picking your battles, but come on man this is pure BS that she is doing. What are your kids learning, that Dad is okay with Mom having a boyfriend because it will keep her from being mean?
Everyone has to do what they think is best in their situation but I really don't see any "best" in this at all. Have you thought about telling her to just go move in with the BF, GF or whoever and set up a visitation schedule for her to see the kids. Then she would be out of the house all the time and you wouldn't have to deal with any of her pissy attitude.
I know you feel like you are in delimna, but perhaps if you take a stand on this it will force a bit of reality into her. JMO.
