Tbh, given that DSD could probably benefit from some 1-2-1 time with your DH and therapy, a move that gives them space is not a bad idea. I think people are quick to adopt the ‘poor child’ stance when, in fact, 15 yo can be manipulative and abusive too. It is very likely that she is ill, whether its an EUPD, trauma response, or the result of some other psychosocial issue can only be clarified by a professional and whilst she is unsupported and not receiving treatment I think you do have to put your younger children first. When my DD was at her worst (ASD/ADHD/suspected EuPD later discounted/suicidal ideation/ROGD) my DH and I explored separating too. We were investigated twice by social services - one of those was a 3 month 360 degree investigation where schools, doctors, counsellors etc were all interviewed, as were both our children. It was invasive and quite harrowing. We were stunned when it was repeated the second time, especially given the positive and affirming comments in the first report.
We didn’t separate in the end because we felt stronger together and because we are are both her parents (and that of her slightly younger brother), but had this been a step child and much younger children, I think we would have been pragmatic. We didn’t plan to divorce, just live separately and it sounds as though this is a wise and sensible option for you all.
It is difficult to find patience and mental resilience for your own children, let alone a child you are step-parenting. The well of emotional resources available to each person isn’t limitless and people who express shock and outrage often haven’t had to tackle it themselves. And woe betide anyone honestly expressing their anger and hate-like emotions when they hit the floor of that well.
@8842688l I know you haven’t posted to ask for advice or help, BUT I would explore you and DC’s moving out for a year or so [or DH can move out with DSD] - just a 2bed flat would do - and seek a referral to CAHMS explaining how DSD’s behaviour has caused the breakdown of the family and is negatively impacting your children (this is a safeguarding issue, so you can actually call social services yourself and ask for help because of the impact on them - we did this as it meant GPs and Camhs took us more seriously).
Hang in there. In terms of my own DD, she eventually did come out of the other side with the right therapist, the right medication, a change of tack from us. There is every chance DSD can too - but to continue doing what you are doing and expecting a different outcome is the definition of madness, as they say. You and DH - with the help of SS/CAMHS/GP - need to shake things up and prioritise other family members for a bit.