What should I do?

I've known this guy since highschool (since 96) a few yrs ago we got close and became intimate.Over 4 yrs we've indulgd n great convo, dates, and we communicate so well, both love the same things..only thing is..he has a girlfriend. now look we were just friends n grew a lil close, i know of his girlfrnd and has spoken to her many times (yea yea i kno, im dirty for that) anyway we lost communication (long story) since last halloween n js reconnected. he's still with her but miserable and trying to find ways to leave her good n kno that he made the right move, this is good n bad news to me, good cuz she was kind of a ***** n kept him miserable n bad cuz he cares for her n i dont wana c him unhappy. i care sooo much for him, being with him makes me feel so good inside. should i tell him and risk losing him altogether or bear what we have to c if he feels the same way? when he leaves her, i want him to come home to me.