Ending online affair?

My husband and I have been very happily married until last year, things happen, lifes little things get in the way and you forget about the important things like date night and stuff, he had online affair mostly with old girlfriend. He wanted to stay and us work it out, I want it to work. Now right at a year, come to find out it has still been off and on, then off and on, its like it is unfinished stuff he says. He has past crap in his life too that has messed with his sense of trusting people to the full. In ways he is really a great person, and he feels bad and he says he wants it to end with this girl. What good ways would you propose that we do to try and end this and get on with our lives? How many spouses know each others email pword, or share emails.