Your H threatened to kill himself last week, and may still be thinking about it now. He needs help, really. He swings back and forth, and he will head back into the not-so-loving again.
He still has a thing for OW, he still talks about her often and hate is close to love. You aren't out of the clear with her until he becomes indifferent.
He needs therapy in a very bad way. He also needs friends if he doesn't have them. HE needs to get a life, because he can't be clinging to you all the time. He should get with a mens group so that he has someone to talk to, to hang with, etc. Maybe sometimes the spouses end up with someone else because they don't have enough of a life to begin with.
