(This is a throwaway acc since they might check my main)

So I (17M) dated my ex (18F) for 2 years. We had a pretty solid relationship, but I ended it because I didn’t feel like I could give it my all anymore with school and a bunch of personal stuff going on. It was hard, but we ended things on good terms and even agreed to stay single for at least 3 months (until the end of the school year) to give ourselves space and time to move on properly.

Two months later, she tells me she has a crush. I was kind of surprised because we’d promised to stay single, but I figured maybe I could be mature and let it go… until she told me her crush was my best friend.

That’s when it felt like a line was crossed. For one, there’s the whole unspoken rule about not dating your best friend's ex. But also, while we were still together, I had noticed my best friend acting a bit too interested in her, and that never sat right with me. On top of that, he has a history of red flags, and she knows this.

The day after she told me about her feelings, they were together. Not even a pause or a conversation, just—boom—dating.

So I decided I didn’t want to talk to either of them anymore. I was still close friends with my ex even after we broke up, but I’ve cut that tie now. I just felt disrespected.

I'm wondering what I could further do with them since I see them at school every day.

So… AITAH?