Worse daughter?

I know how this might sound but I can’t help it
Long story short, dad divorced mum, married my step mum, I have 2 half siblings and I don’t have the best relationship with my step mum. She often gave us the silent treatment and didn’t care about our mental wellbeing. She looked after me for 19 years but as long as I remember the relationship was odd and got worse after my half siblings were born. We would have arguments then I’ll get the silent treatment then repeat. It’ll be months where we don’t speak and I cared as I knew I was the child in the story but often blamed myself. I struggle with internal issues and anxious thought when we argue and wouldn’t leave my room or eat when she’s home. The anxiety reduced and I can leave my room when she’s around but can not make eye contact with her or my half sister. Which means my relationship with food, my dad and siblings are trash. I can’t go eat in the living room with family as the anxiety around them is at all times peak and the paranoia. It has gotten better.
What’s my solution? I thought maybe being on talking terms again but I’m not ready for the cycle and waste of time. She’s pretty good with mental games as she’s a narcissist so I feel maybe I’m the problem (as she said) and i need solve this issue and I’m hated at home as obviously I won’t leave my room to do anything nor even help around (which makes me feel even worse as I really like cleaning) but refuse to do so when she’s here. Too much anxiety

The problem is not with you, it is with your father's 2nd wife. Your father should have been looking out for you more through all of this. I know you said your relationship with your father is trash, but could you talk to him about this, about how his wife is making you feel? It's a shame that the relationship with his new wife has also caused a strained relationship with your half-siblings, they are probably picking up on their mother's attitude towards you. If there are opportunities for you to spend time with them away from the house and away from the parents, this might help you build a bit of rapport with them and could help you join in to the family situation.
Side note, where is your biological mother in all of this? Would it be possible to stay with her? It would be a better environment for you I am sure.

I can sort of understand what your going through as you've explained it really well but i can only suggest you build a relationship with your step mum and half siblings as you don't get family twice and family time should be enjoyable, try playing monopoly or PlayStation with you family and take away the awkward tension.

Is there any other family you could stay with? Or any feasibility to move out? I think being out of this environment might be the best thing for your mental health.
If not, you could ask for a 'family meeting' to air the grievances and see if you can all move forward from this.
Sorry I don't have anything else to contribute here but I hope things will get better for you.