With all due respect to what's already been said, getting your husband on medication, working with a psychiatrist, and getting him dedicated to his health is the one thing that could change the outcome of your marriage.
When your husband tells you he loves you, then says he doesn't, then wants sex, then wants to be out at bars all night, he's responding to what his brain is telling him in that very moment. That's how bipolar disorder works.
It took my husband over two years and three doctors to finally find a doctor and medication combination that gave him any semblance of stability. It takes patience. In the mean time, he said some really outrageous things to me and hurt me deeply. In the beginning, he went into a psychotic stage, threw me out of his life, and slept with a co-worker. He doesn't remember any of that, he only knows what people tell him. Believe me, I've been there, and I know how it feels.
I don't know exactly why I let my husband back into my life when he began to show signs of recovery (but long before he was actually stable). Probably because I love him immensely and I always held great hope that he would ultimately achieve the kind of stability that so many people with bipolar disorder do when they are properly treated with medication and counseling.
We do have a stable, loving marriage now. Albeit, his current medications have eliminated his sex drive. (Harder for me than it is for him; I miss the intimacy and I'd like to be able to have a baby in the near future.) He's working with his doctor to alter his meds so he can have a sex drive again.
It's a process, and it takes commitment. But what worries me from your story is that it takes a huge commitment from the patient, not just the patient's spouse! If your husband is not willing to commit to taking his meds, working with a psychiatrist, and giving his all to get better, there really is nothing you can do, and you may need to consider walking away before it consumes your life.
But on the other hand, bipolar disorder in and of itself is not a hopeless situation. Much like diabetes, bipolar is not cureable, but it is very treatable. It just takes a lot of energy and effort to get there.
Good luck!