Boyfriend talking to ex in the gym?

Boyfriend cheated on me in the first few months of dating, back 3 years ago. I thought we were in a relationship, but he clearly was lying. I went back and we are all good. No issues. But the girl he got with has a huge obsession with him. She stalks me on social media all this time. Has my Spotify playlist saved etc. my boyfriend is a fighter and teaches a class once a week. She moved county, but is back for a few weeks. At the class today he talked to her. She knows it’s his class and still showed up. She pretended to everyone that she was pregnant with him before, spoke bad of him etc. she talked to him tonight and my boyfriend said that she told him that she moved aboard and she asked him is it true that he changed jobs and that he works in a hospital now. She’s clearly doing her research on him. Am I wrong to over react with him talking to her?

Boyfriend talking to ex in the gym?
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