Why is it my ex is so obsessed?

Okay a little back story. I broke up with this guy about the beginning on this year and I told him that it just isn’t working out and I’ve lost feelings. He got mad and tried to use my photos and blackmail me, to make me stay with him. I immediately left him and every boyfriend (2) I’ve had sense then he has hit up threatening them and sending them my photos and calling me a slut and all these names? He already had posted my nudes online and I can’t do nothing about it. I just want to know why he’s doing this. What’s ur opinion?
Why is it my ex is so obsessed?
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