This is a sad story. I think you did the right thing by asking Bipolar people because we are the only ones who really know what it feels like. Everyone else has to rely on buzz words to obtain simple rationalizations of a complex situation. This is even true for the doctors.

First and Foremost: Medicine. He must take his medicine. If he stops taking it then it is because of one or more of the following:
1) side effects
2) lazy
3) they aren't working
4) financial/health care
5) No confidence in his doctor

Figure which of these apply. Make the proper adjustments.

When we are in mood episodes, our perception of the world changes. It is very dramatic and you cannot break the cycle with words alone. Words do help. You need to convince him that he can achieve inner peace and feel good like he did during his happy times. Explain to him (because he does not realize it yet) that his view of the world, other people, and inner musings are all skewed from his original personality. Tell him that a good doctor that he trusts and the proper medication will eventually make a dramatic improvement.

I am biased when it comes to medicine. With that said, let me shamelessly suggest Lithium ER 900mg daily and Lamictal. I went from suicidal to completely normal after 6 days on Lithium.

Good luck and check back in with us for updates.