From reading your sitch... I think your H wants out because he's tired of feeling guilty and this guilt only adds to depression.

My guess... when he tries to get off the fence and come over to the side where his family is at he has too much guilt and this guilt only makes his depression worse. I don't think he really wants a D. I think he feels there is no alternative. He feels he has hurt you so much he needs to leave. I could be wrong, but that's my impression so far...

Was there more than one A?

Are you the one who contacted the lawyer first?

There is no arriving, ever. It is all a continual becoming.