Samoascookies, I am the spouse to a BP. NO...being regulated on meds or not, it is not easy. It can be lonely. And believe me, my man is a good man, well intentioned with a very loving heart. The problem is, I see it for others most of the time, not enough towards me. I get the bulk of the brunt of things. I am sorry for you that your wife has chosen to leave, for her...I will not judge her - this is a HARD life and a person can choose not to have to live it anymore. We spouses, and our happiness count too.
The fact is, if you told my H what it is like for me as a result of his behavior...he would not believe you. He is CONVINCED his perspective is right. He doesn't see the issues, or experience this side of it the way I do, and he won't even acknowledge it exists. In other words, he won't connect the dots. NOW...with that said...do I think you can be so traumatized from a breakup with her so many years ago that it has been the trigger to all the "issues" you are having? No. That isn't to say there may not be unfinished business about it. But to be such a significant trauma the way you are describing....IMO...no. I think you are just very sad, because you would have desperately liked a different outcome than what you have. You have a right to this sadness, but keep it in perspective too. Get the help you need, get control of your behavior and life....and go find your smile again. If you do this, and REALLY own your dx, and are totally responsible about your behavior about it forever more, one day you will find another partner and you will be happy again. The opportunity just may (or may not) be over with her. Only time will tell.
What to tell your daughter...the truth with all the love and respect you can. "Daddy & mommy love you. We love each other too, but because of grown up things, our love changed and we decided we could be better parents to you if we were better friends with each other, than we were as husband and wife. We will always love you, we will always take care of you, we will always be friends and love each other because we made you together." And then you back that up by treating your potential ex with total understanding and respect for the (I'm sure) very hard choice she is making. And be the best co-parent you can be. As your child asks more questions as she gets older...just always tell her the truth. Explain that, "daddy has this condition called BP and as hard as you tried, it was still hard to live with for her mommy. Sometimes without meaning to, daddy did not always act as loving as he should have, and was very moody. This prevented mommy from being as happy as you, her husband, wanted her to be, and together you decided to help mommy get her smile back by respecting when mommy said she didn't want to live together anymore." You tell her you understood and are not mad at her mommy. And then you go on being the best friend and co-parent with her mom you can be, and let her see your care and respect for her mom that way. THAT is all kids need under conditions like this.
Best wishes to you for wisdom, enlightenment, insight, and peace. LFW