Feelings of shame for lacking boundaries and self-esteem

I feel overwhelmed by feelings of shame knowing that, while I am completely intellectually aware of the abuse taking place, and even recognize them in the moment, I still never muster the strength to set boundaries that are actually worth something. Even as I write this, I'm cringing at myself because I'm worried that I have taken on the 'woe is me' spirit that often characterizes their shame spirals. Then, I think, I'm just as messed up as they are...I don't even want to leave...I just live in constant, anxiety, repeating the same caretaking role I've taken on for as long as I can remember with my personality disordered father, and my brother with bipolar 1 (who had a near-fatal accident last summer on an electric bike during a manic episode with psychotic features after breaking his sobriety after fentanyl addiction & heavy weed smoking). I feel so vulnerable and weak, I just feel so worried and for all of these loved ones in my life, including my pwBPD, and I just feel helpless in the face of this pain....but I know that I am getting so, so tired...I admire those of you who really do have veritable self-esteem, who view your own happiness as paramount. I'm just not there, and I feel so embarassed and ashamed.