(I'm on mobile, sorry,)
Hey guys :)
Hope my post is allowed here, if you wanna remove it that's okay too.
My sibling (23, non-binary, amab) is on promethazine, lexapro and 5mg resperidone for over a year now. In July 2020 they told me their psychologist is expecting they will develop schizophrenia in the future. Shortly afterwards they got hospitalized for 3months to be stabilized.
Right now the meds won't stop them experiencing positive or negative symptoms. They told me they are about to get diagnosed with schizophrenia.

I already talked with my own psychologist about that and I feel so helpless when I try to help them or myself in this situation:
First of all I wanna validate them when it comes to their gender identity. But they getting are more and more detached from reality, their personality is changing and I also don't wanna confirm their delusions or encourage them to permanently change their body. I know they first told me about their dysphoria in their teens, but right now, it feels like a rock and a hard place in how i talk with them about that topic. And if  they are right about their gender identity i am scared nobody will take them seriously with that in the future.

Also they talk with me without the ability to emphasize with my own situation: they are telling me about their suicide ideation, the weird stuff they find on the internet and confront me with some stuff my PTSD-brain finds really triggering. I already told them that with my past it's hard to digest what they are telling me. But they won't stop and i am getting mad at them.

I wanna help them and I don't want them to further isolate themselves from me and my parents, but sometimes they really hurt my feelings and as I said I feel like I can't help them. I already asked them if they wanna be in hospitalized care again but they won't budge.
Also: they don't keep away from drugs which is concerning.

How can I help? I really don't wanna lose them.
(English isn't my first language)