I'm a guy, and i've dated my share of ladies with issues. I put up the post "my girlfriend cheated on me". But to answer you question, yes tell him! Dealing with a lady with issues is hard, but some men are able to deal with it. If hes not, your just asking for more issues. Some men are not mature enough to deal with the ups and downs of bipolerism. If hes not, its not going to be a healthy relationship and that would be waisting yous and his time, and life is to short for that. Be honest with him and let the chips fall where they may. In the end you'll be glad you did. Nobody wants to be in a relationship that has no future. If you start your relationship off with secrets, thats what you can expect down the road, more lies and secrets. If you dont tell him, trust me he'll be able to pick up on it anyway, and the fact that you hid it from him is going to make it hard for him to trust you down the road.