Thanks, that sounds really stressful. Your gb2 sounds immature, manipulative, and very controlling. Are you wanting to stay in touch with your Mum? That is terrifying he has so much power over her. You are doing the right thing by not giving in, you owe him nothing.
I really wanted LC to work with dm, but in my case things only got worse, especially with my young dcs involved.
I think in my situation it was triangulation with dm, my estranged sibling (golden child) and me (the scapegoat) that hugely complicated things. Dm and golden child are very much alike so a criticism of him is a criticism of her if that makes sense. I am similar to my late dad and he taught me what unconditional love was, (he died acouple of years ago, parents were divorced for 20+ years).
What made me wake up and realise was when dm wouldn't take any accountability for anything, and did the classic DARVO, to my face in my own home after I waited on her hand and foot for an entire day, and she then did it again on WhatsApp after I had been grey rocking (dm would not accept the low contact and I was apparently "driving everyone away." (Everyone i am assuming is her and sibling 🙄) Dm was estranged from close relatives, lost loads of friends and quite honestly I was lost for words.
Within it all dm insulted my df on the month of his death anniversary blaming him as well as the child and teenage version of me; she is a vindictive emotionally immature person, cluster B narc, (covert and overt I suspect).
The irony is that Dm's invalidating of my whole existence actually validated me in the end, because it made me see a lifetime of not feeling good enough and not feeling liked let alone loved by her wasn't a figment of my imagination; it was sadly the truth. I could never in my wildest dreams imagine telling my adult daughter what she told me. I had been striving all of my life to please her, clinging on to a tiny piece, a fragment of hope that maybe just maybe she had goodness in her, it couldn't be true, she had to have feeling behind the coldness. You could do 10 things for her, she would forget and focus on the 11th you did not do.
I am 40 with 2 young children and realised dm was affecting my health. I put my dcs first, they need their Mum healthy I cannot jump through hoops or pay the price for low contact with dm; it wasn't healthy for my dcs to witness either not a good relationship model. No matter how hard you try, there is always an elephant on the room, and eventually it just isn't worth it.