My mum is toxic and I feel trapped

My mum and I have always had a rocky relationship.

Growing up, we constantly butted heads and she'd say things that would really hurt me like wishing I was never born, telling me I ruined her life and nobody likes me (to name a few). When I went through something traumatic when I was younger which involved an abusive family friend. She sided with him and blamed me, even though I was the victim in all of this. It was a really dark time which still impacts me to this day and I've never fully forgiven her for it.

Even with all that, I've tried to keep some kind of relationship with her, but being around her drains me. She's always negative and manipulative when she wants something. I feel like she only keeps contact because I'm useful to her, not because she cares about me or my life. She has absolutely no interest when it comes to anything to do with me.

What makes everything harder is that one of my siblings has special needs and she depends on me to help advocate for him. That's honestly the only reason I haven't cut her off. I want to be there for my sibling and since she's always with him and needs help with him, I can't avoid her completely.

She guilt trips me and pushes me into doing things I don't have the capacity for. She has no boundaries and will call nonstop until l answer, even if it's something that could've been a quick message.

She's even cried about feeling like she can't come to me for help, which isn't true at all because I'm the only one in the family who actually helps her and will drop everything to do so.

Any time I try to set boundaries, I end up feeling like a bad daughter. I want to distance myself, but | can't because of my sibling. I feel drained and low all the time because of how she treats me. She makes me feel small and things with my dad aren't good either, so l've held onto the rare good moments with my mum in the hope that things will improve, but they never do.

I'm not really sure why I wrote this. I guess I just needed to vent and get it out because it's been eating me up.