Hello everybody, I am back. We did go to AZ for the weekend and things were better (though I had to practice a lot of thought-stopping).
Though we nearly didn't go: H came back at 10 pm on Thursday and I was really nice and understanding, but on Friday I was watching him like a hawk. He got mad and snapped at me with a "this cannot go on". Instead of begging or backing off I calmly agreed that he was right. It could not go on while she is there and I did not want to go back to how we were. So I said I would go to AZ (it was a bussiness trip for me) and expected him to leave when I came back. Then our D and I left for carpool. I had not gotten down to the main road when he paged me and I was just at the school (5 minutes away from home) when he called my cell phone to ask what I was going to do with the dog (we had planned on leaving him at the vet while we were out). I said 'it depends, if you stay I will leave him home'. The upshot of it is he agreed to come and even called later to say he was sorry. I chose to see it as a small step forward.
I do not know what she is giving him. My SIL thinks she is a manipulative b**** that wants him to provide for her and her family. I think it may be that he feels she needs him (both her and her daughters work for him) or that he cannot confront her. Her has always had a problem with confrontation, especially confronting women. He says OK, then simmers and resents. I used to joke that if he were a woman he'd be a whore because he cannot say no. I am quite happy that he actually confronts me now when he does not like something.
I have done a bunch of things and they have helped. I do not complain or nag or tell him what to do... My goal is to get rid of her before Xmas. if at all possible
"You don't throw a whole life away just 'cause it's banged up a little"
Tom Smith in "Seabiscuit"