Kathy, you aren't stupid at all, you want to believe her, which is a natural way for you to react............ and she is in the throes of alcohol, Borderline (BPD) and bi-polar, a combination which alters her brain so that she makes decisions and lives her life from an entirely different point of view. One which you, me and most of us, don't share or understand. Even though her behavior hurts and disappoints you, I don't think it's at all directed at you or anyone, I think, in many ways it's the best she can do with what she's got. Relapses are part of recovery, I've heard that a hundred times in the program I'm in, AND, each relapse goes down with more and more recovery, even if it doesn't look like it to us. She managed to not go to Colorado and keep her job and continue with her therapy, all positive signs along the way. But, I know from talking to my sister and daughter, that the alcohol/substance can soothe all the internal demons they live with, make it easier for them to accept themselves, especially under circumstances where there is loss involved, as in the ex boyfriend. I'm not saying that is a good choice, I'm just observing that it is a common choice to relieve the anxiety, the fear, the lack, the turmoil or the sadness. Their path is not a linear one which is headed in an upward motion, it has a lot of detours for them, which makes their recovery so much harder on them and on you.
I am not condoning any of this, I'm just trying to offer a different perspective, one which I've gleaned from listening to my family over a lot of years so that I could recognize that mental illness and personality disorders make just simply living life an ordeal, sometimes a nightmare, which we can't know because we're not living in those shoes. But we are dragged through their world over and over again so our hearts are worn out and tired of the insanity of it. I get that, I really do, I've lived in this zone all my life. Your difficult child is just who she is, perhaps doing the best she can, maybe not what you would like to see, I understand, but she's the one with all the challenges she has to face and overcome and as we all know, they self medicate. And, we're the ones who pick up the pieces when they fall, which they are inclined to do. over and over again.
I have a very soft spot in my heart for your daughter, there is something about her in your posts that touches me and makes me feel that she really, really wants to be the person you want her to be, and often she fails, but it isn't for lack of trying, it's for all the internal barriers inside her which keep her stuck in her own world. I think where some of these kids live is a kind of hell which we really can't imagine, and yours has been doing a pretty good job of staying on the straight and narrow. And she fell. And, then you live in your own hell. I am sorry, I do know how hard it is to watch them fall. But, I still have hope for your difficult child, I really do.