My brother's girlfriend is bipolar. He went through basically the same situation (except, they also have a one-year-old daughter). She (who is 25) has been unmedicated since she was 15. When her cycles started becoming really severe within the last year, my brother basically gave her an ultimatum. He said that she either needed to agree to go to counselling/therapy/whatever or leave. I know it sounds harsh, but it was safest for him and the baby.

Dealing with someone who is bp is hard (I know, I see how I've affected everyone around me) and sometimes the person who is dealing with it doesn't realize what they need.

I'm in no way suggesting you should just up and leave this guy. I don't know the situation of the extremity of his symptoms. But I do think (if you do agree to get back together with him) there should be a promise of some type of therapy, either for him or both of you (ideally, both kinds).