Good for you for seeking answers! That is a brave thing, so be sure to give yourself credit. You are on the road to improving your life, and that is exciting!

I can't honestly say that I've experienced anything similar, but, if I may, what you describe sounds more like borderline than bipolar. Of course we can't dx or anything, just an impression, what with so much revolving around relationships, "abandonment" and the sudden "on-a-dime" type mood turns. Regardless, it sounds like you might find DBT (dialectical behavioral therapy) helpful in navigating. Have you heard of it? A lot of people have found it really helpful when they feel their emotions control their lives overly-much/cannot control reactions, as you mention. For whatever reason that is occurring.

Like Tucson said, please do not be too hard on yourself. You are being wise. You are seeking answers. You are seeking a better way. We can't change what is water under the bridge, only use it to understand and go forward.

Best wishes! Keep us posted how it's going, ok?