Hope for bipolar relationship ?

Hello. I've been dating my boyfriend for just over two years now. We are currently long-distance, though we didn't start out that way. In his current location, he has very few, if any, real friends. He's also an only child with a very difficult family life. He was diagnosed with bipolar disorder when he was in his early twenties and was on medication for awhile and seeing a therapist. He did not have good results - particularly with the therapist(s) - apparently, and has not been actively engaged in treating his disorder since (though he has occasionally gone on anti-depressants he's purchased on the internet for brief periods of time. Not the best idea, I know). He is, however, taking prescription meds to help with his concentration. Anyway, we're currently going through a really rough time. He's been depressed a lot lately, and he's engaged in trying to finish a really difficult project - he's writing a book - and feels that his entire professional life depends on it. A few weeks ago, he broke up with me, saying that he couldn't focus on anything but his work because his life is falling apart. I said I was willing to wait for him since the problem is external to our actual relationship. We had been fighting a lot beforehand, however, mainly because he couldn't spend any time talking to me and I was going through a rough patch professionally as well. We spent some time together recently, and it was off (whenever he was talking/thinking about work, his family (we visited them), or our relationship) and on (the rest of the time) good.

After we parted a few days ago he was very communicative until today, when he sent me an email saying due to the pressure he's under he may not be able to be in touch with me, but will try when he can. This..was a hurtful thing to hear. He has also told me that while he loves me and wants things to be different, he feels like he has absolutely no control over this situation and that what he's doing is about his survival. He makes no promises about things being different in the future because he says he can't think about the future at all. But i love him. and while i know the future is uncertain, i think he's worth waiting for. I guess we're officially in some sort of limbo, where I'm working to maintain the relationship, such as it is, and he's...doing what he can. I don't know if this is the best thing for me, but I think it's the right thing to do. Anyway, I don't really have a specific question, I'm just wondering if anyone has any experience with or thoughts on a situation like this.