My actual advice would be to practice trust, honesty, humility, and compassion. Seek to be a better you, rather than compete to be like someone else. Trust your husband's words that he wants to be with you. Seek professional counseling. And have a heart for your husband's girlfriend; it is the ethical thing to do.
I keep having a little bit more to say, but I think I've said most of it.
I agree that this thread has been a rough ride. I feel sorry for all three persons in the situation, but like I said, I feel the worst for the husband's girlfriend. I wouldn't know what to tell her other than to set a timetable, and run for the hills when the time's up.
It's sad to read of such things.