Well, I am NO expert. But, I think he may be the one who should be the recipient of a letter and too bad if she doesn't like it. That is assuming you care about him and want him to know that this has nothing to do with him etc. Maybe write it and post it on here for some feedback. Obviously, you shouldn't step on her toes or badmouth her but I think you can say your peace to him.
If she is taking him with her to OM than she is really f'ing with him. What can you live with? What is your bottom line? Most people here say don't leave the house. Can you see a lawyer just to get an idea of what your rights are? Your self-care MUST come first now. I know it sucks but it will help. Exercise, write, read, do things you've always wanted to do and really see a lawyer so you don't feel so vulnerable (and she doesn't need to know).
