She spends her money on weed, her nails and door dash. . .
She is not competent and has poor executive functioning. She doesn’t keep her psychiatric appointments and tends to lay around watching television much of the time. . . . This recent episode was precipitated by her going out . . . Her response was to lock herself in her room . . . I told her that we needed to discuss her contribution to the house. . . . She went from zero to one hundred and headfirst into a splitting episode. As a parting gift she left me (crap).. . .
OK, excluding the the baby and abusive childhood, I could have written the exact same thing about my adult BPD stepdaughter, when she wasn't getting treatment. Correction: when she was skipping her psychiatric appointments but we were billed for them anyway.
My observation is that weed consumption turned her my stepdaughter's already questionable executive functioning into total dysfunction. When she was using daily, it seemed she couldn't think straight, let alone plan, let alone do simple things such as remember to pack a bag for a weekend trip. She had bouts of paranoia when under stress. I think weed turned her occasional procrastination into total avoidance of life, and completely sapped her already low motivation. Between weed and TV, she made herself comfortable retreating from the world and any adult responsibilities. She was able to do this because she was living in my house for free, with no contributions or responsibilities, either. Her dad gave her money (out of guilt) so she wouldn't go without. Yet without the necessity of working for money (not even a simple household chore to earn an allowance), she basically locked herself in her room and stayed entertained with weed and screens. At the same time, she was seething mad and took out her frustrations on anyone who would listen. Since friends wouldn't put up with her hostile behavior, she lost every last one of them. She became estranged from her entire family--siblings, her mom, her aunts and uncles, cousins, grandma, etc. She'd only talk to her dad and me because she needed free housing, money and other support. There was no love or concern there, it felt like a purely transactional relationship.
I felt that my stepdaughter was compelled to say the nastiest things about her parents to convince herself that she was victimized and traumatized. That way, she could embrace the identity of victim and escape the deep, looming shame she felt for sabotaging her own life. She is the one who made bad decision after bad decision: quitting school multiple times, quitting work multiple times, getting herself evicted multiple times, getting herself in dangerous situations, losing all her friends, quitting therapy, committing various acts of self-sabotage. She blames her family, even though they had absolutely nothing to do with any of that. Deep down, what she was doing was trying to shift the blame for her own dysfunction to family. The barrage of accusations seemed cruel, constant and yet also delusional. What I saw was that the barrage was mostly a deflection, a distraction, a sure sign that my stepdaughter had made yet another poor decision. She'd lash out and rewrite history in an attempt to blame-shift and avoid responsibility.
At the end of the day, I think it's really hard to have a loving relationship with someone who won't take any responsibility for their own decisions and blames you instead. Like you wrote, it's not fun being a pin cushion. Maybe you can take it for a while, out of feelings of love, fear, obligation or guilt, in the hopes that she'll stabilize and get the help she needs. But that's not a foundation for a normal adult relationship, because there are two adults involved, and both need to try in a relationship. If you feel that all you have done is tried and tried, and yet your daughter won't acknowledge any of your efforts--rather, she RESENTS you for having tried so hard and still BLAMES you for her horrible life--then it's OK to protect yourself. My guess is that you want her to get therapy more than she does. You want her to have a stable life more than she does. You want her to love and protect her child more than she does. But it seems to me she doesn't want your help. She wants to do whatever she wants whenever she wants it; she doesn't care if she's being cruel to you or even to her own baby. So it's OK if you take a break from that negativity. Let your daughter do what she wants, as long as she bears the consequences, not you. It doesn't have to be forever. How about, just start with today. Give yourself some space and grace. See how that goes. I sincerely hope it makes you feel better, if only for today.