Why does my ex get so bothered being in my presence?

I literally do not bother him, don’t talk to him, don’t look at him and haven’t for months but we are forced to be in the same place once a week. All he does is talk about me to mutual friends and try to continue this petty drama when it’s been months since we’ve broken up. It bothers me because he tries to act like a victim as if I’m harassing him every time we see each other , when in reality I don’t even look in his direction.
Why does my ex get so bothered being in my presence?
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