A lot of the behaviors you are mentioning makes me think that he's been depressed. Just the non-communicating nature he's been having and the ****ing around with meds. that really doesn't help. I feel you need to look into therapy. Your posts say that you choose ***es to treat you bad and you blame yourself for them being ***es. Yes BP's everything is more intense. I'm wondering why you are trying to learn as much as you can about it? Do you feel you'll go back? or are you calming your insecurities of the brake up? or are you worried about yourself?
I do feel him telling you about his MI was his decision and should not have affect how you respond. He was the same *** with or without bipolar.
Now the question of talking to his mom, have you ever approached her with the MI topic? Whether family is close or not that may be a closed topic.

now I'm sorry, I have to comment on some of the more negative things you said, but I'm not saying don't stick around.

I think the co-dependency group will probably help you a lot.

I feel you don't need to know a persons Dx to "know them" or "be a better partner"
Ability to communicate effectively has nothing to do with being bipolar unless the person is in a severe depressive or manic state.

If we choose to take medication it's not for major events like break ups. It's to keep our highs and lows in a range that we don't need consent hospitalization. Possibly attempt goals like working, driving, education and a family.

I feel most of us our painfully aware of the issues our moods cause our families. That's why suicide often looks like a solution when seriously depressed. Mentioning we have a 90% divorces rate feels like a cheap shot.