Thanks Sandi. Things are not always as the seem as we know. Everything in my gut and heart is telling me this is what's right for me. I'm just going to have to take it one day at a time.
I don't think he can take all of this on long-term emotionally. As he's said he's got his own issues to work on. I'm praying that once the situation stabilizes that he will start to back off. I know he knows he'll need to do that.
Remember, the first night this happened he said that her H told him not to tell me (about her suicide attempt)but my H said I just couldn't do that he didn't see how he could not tell me. He was so angry with himself for allowing himself to get caught in the middle of the two of them. He even thanked me for "not being crazy."
Maybe I'm delusional but it appears that my support of him is having a very positive impact. As I said, he calls me at work when there's an update. We've been talking every night at home as well.