Tired of drama,
I'm glad you're dealing with the issues of codependency. I hope that you'll teach your children that too, as they grow old enough to understand. (You don't say how old they are.)
Continue to keep up your boundaries. Make them simple and clear to him, and do not deviate from them. When he violates them, remove yourself from the situation immediately. Victim mode or not, he will learn what will be tolerated and what will not. And you'll be setting a fine example for your children too. they will learn how to set limits with love. For them, that's essential.
My ex is not bipolar, but, I have no doubt that he's an undiagnosed depressed man. His anger and his irritability and his irrationality can play havoc too. For too many years, we danced the dance of anger together. Today, I get off the floor. When it starts, I hang up. Of course, our son is now an adult, so, there is no longer much we have to deal with. That day will come for you too. It's not too far off. In the meantime, please try for your children. They will come to understand, one day.
Shalom!