Betrayed by my cousin?

In my final yr of highschool my 'close friends' started ostracizing and bullying me (isolating me, calling me worthless, mocking me, locking me out the door and laughing at me) to the point where I developed clinical depression. I failed my uni classes the next year and after 2 years of suffering, I finally decided to get help. My cousin only knew of my friends through me but he wasn't friends with them. Once I confided in him about this and how I self harmed because of the bullying I experienced. He pretended to care for me but shockingly went behind my back to join hands with my bullies (since they're a bigger gang). Since they were already ganging up against me, my cousin joining them made them even more powerful.

I tried ending ties with my cousin after this, for which his siblings are now calling me selfish and evil. What should I do?

Betrayed by my cousin?
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