what should i do

In love? You mean you have a crush on him.

in love? you mean tricked? your story is not unique...men are really good at being two faced. so, he showed you a nice persona, made you think that he was this wonderful guy - sweet caring charming, creative, funny, intelligent - and I imagine that maybe his marrige is no longer close, is that right? his wife is sometimes distant, they dont have sex like they used to, they dont talk like they used to, etc etc blah blah...and now you are the sweet young woman who has waltzed into his life like a ray of sunshine, makes him laugh, who he feels he can really talk to, and really understands him... don't buy it, its all an act. He has seduced you. He is playing both you and his wife for fools. And for god's sake, please do not do anything impulsive! Your first priorities are yourself, and his wife. This lying cheating manipulative sack of shit, and his needs, come last, do you understand me?? YOU AND YOUR FELLOW FEMALE COME FIRST. That is the way you must think and what you are going to do will follow from that.

we have a femi-nazi amongst us, females unite.

If he's married...leave it alone. That should be enough. If he says he's happy or not..that should be your clue. Married men or women are OFF LIMITS!