Where is my relationship with my brother headed now?
My brother has a new boyfriend and since getting this boyfriend, the trust in my relationship with him has disappeared. We are both in our thirties; he lives with our parents and I come and visit from time to time. Our family relational system under our parents has always been characterised by narcissistic-codependent patterns to a greater or lesser degree; it's pretty 'textbook'. But his complicitness with me has eroded since the start of this new relationship. He has started to be mean to me for inexplicable reasons, and he will will join our parents in berating me even when it's clear that they are being completely unreasonable.
Now, the backstory. My brother knows that I do not understand same sex relationships to be something that pleases God (Christian God) and that I would personally rather he didn't have a boyfriend. We had that conversation a long time ago when we were teens and he first talked to me about his sexuality. It had been a heartfelt, vulnerable conversation and it had ended in mutual respect and "thank you". Since then he has heard me say time and time again that I have heard him, and that I accept him because he is my brother, and that I've got his back. I never presented as an 'enemy' to him before - even moreso because I admitted my own experiences of same-sex infatuations to him. For a long time I was the only person he'd told, and I know that our (non-religious) parents aren't even willing to hear him and take him seriously. In fact, our father has directed deliberately offensive words at him about gay people to try and 'put him off', in the same way as he once bullied him out of his curiosity about Christian faith.
The problem for me personally is that since getting his new boyfriend my brother has started speaking to me unkindly (e.g. telling me to be quiet because he can't hear the TV in an unnecessarily cutting way, with an insult attached), stoking disagreement between my parents and I, and getting our parents to agree with his story (he is the 'golden child' in Mum's eyes; I have been the scapegoat for as long as I can remember), generally not having anything nice or friendly to say to me, and being uncharacteristically mean. Not just blunt or unsmiling, but passive aggressive and cutting. He has a lot of charm and he seems to switch it on and off. He seems to use me to vent negative emotions more than he used to.
I just want my old brother back. The one who was vulnerable with me, who complicitly agreed with me that our home life was dysfunctional and that our parents' behaviour was out of order, and who would never take their side against me in one of their senseless tirades over something I was supposed to have done. The one with whom I used to be able to have deep conversations in good faith and he didn't get defensive or try to use my words against me. In short, he is becoming just like our parents when they're 'acting up'. I feel like I can never quite trust him not to betray me to them.
Why is this happening? He has had boyfriends and male love interests before and he didn't turn on me like this. Could it be that his boyfriend is encouraging him to hate me because of my beliefs about gay relationships and God? And irrespective of why it's happening, what should I do about this breaking-down relationship, while remaining true to my own self and values? Why is my brother becoming this kind of person to me? He knows that I have never turned against him, that I know what it is like to be strongly and almost exclusively attracted to members of the same sex, and that I have cared for him greatly before and after knowing his life choices.