Problems coming out to accepting family

My mom and dad have asked me many times why I've never had a girlfriend. Over the last couple months I have realized I'm gay. However I can never answer them straight up because we have a very large emotional rift that is hard to get over. I am also bipolar and I discuss this a lot with my therapist. I realize there is no set time that I "should" come out but it's just extremely hard because I only feel comfortable telling my close friends who I really am and not my parents. They would be extremely loving and accepting, which I am grateful for. I just have this feeling like I can't tell them.Has anyone ever been in such a situation? It's a pretty stark contrast to many gay men. It's kind of odd. I'm just looking for advice.