Sorry for your pain. When the heart hurts through loss of a relationship due to death or circumstances or whatever, it just takes time to heal.
Perhaps there are some positives here, though which may ease the pain in a small way. If I were one of your personal buddies that you hung with on a regular basis, I would never say this to you for fear of irreparably harming our relationship if you got back with her, but since I'm not, I don't have that concern, so I'll say it: maybe you were just dealt a winning hand by the big guy up above (or the fates or blind luck or whatever else you do or don't believe in)to have this relationship end. There could be many reasons for this to be eventually perceived to be fortuitous. One is the bipolar issue and the other is that this will free you to potentially meet your true soul mate.
Bipolar disorder is a lifelong condition with varying degrees of severity and responsiveness to medication. Since a marriage is ideally (although, obviously in reality not always) for a lifetime, that's an awfully long time on a roller-coaster with a lot of peaks and valleys. I guess that could mean a lot of great make-up sex, but perhaps also a lot of time in turmoil and conflict. In addition, should you get back together and either continue the relationship and/or get married and eventually break up over the same issues, aside from the "sentence" you would be serving, hopefully there are no children involved to also get hurt in the breakup. Also, bipolar has a high genetic component to it. Just some things to consider in possibly perceiving your "bad luck" as "good luck".
As far as relationships go, unless you live in a monastery or hermitage, you ARE going to meet other women. I know that thought isn't really appealing to you right now as you perceive this woman as "THE ONE", but the human male's biology makes him incredibly adaptive and pragmatic. And since sexual desire underlies and drives most mating relationships, you will have sexual desires for others which then will present a chance for meaningful relationships to take hold. Let me put it this way in a somewhat strained but nonetheless still valid analogy: If you were marooned on a desert island with some terribly unattractive fertile woman for the rest of your life, after a while there would be plenty of little (probably unattractive)kids running around eventually. The pessimist might view this as "settling", the optimist would view this as making the best of the situation.
In no way do I suggest that you "settle", but rather that you view this as an opportunity to meet other women, any, all or none who could make you happier, ultimately, than this one.
Good luck, pal. Many of us have been there and many of us will be. Such is the human condition. You are not alone.