My Ex and a good friend started dating

Hi everyone, I’m looking for some outside perspective because I’m not sure how to handle this situation.

I (24F) dated my ex (26M) for about three years. We lived together briefly after the breakup, which happened because he came out as gay. We stayed on good terms and are still close friends. We also share the same friend group, so we see each other regularly at social gatherings.

A few months after the breakup, a guy in our friend group (let’s call him John) asked me on a date. I wasn’t interested in dating at the time, but a mutual friend set it up, so I went. I had a good time but didn’t want to pursue anything further. This was about two years ago.

Since then, that same friend would occasionally tell me that John was still interested and would “take me back in a heartbeat.” Over the past summer, our friend group hung out a lot, and John was flirting with me quite a bit — this was noticed by others, not just me. Despite this tho we still had a lot of fun hanging out and were good friends

About a week after asking me about my friends, John started hooking up with my ex. My ex told me about it himself. I told him I felt uncomfortable and that it felt like a betrayal given the context. He said it was harmless and that they were just friends with benefits.

Since then, they have become an item and have said I love you to each other. I don’t want to stop them and I want them to be happy but I feel like I have lost my safe places. my ex was a safe place but has betrayed me, My friends tell me its none of my business (which is true and I don’t want it to be), but I just don’t know how to feel better about it. I don’t even talk to John anymore and John became good friends with my sister and brother in law so my online space doesn’t feel safe anymore (we all played games together).

Because we’re all in the same friend group, I often end up seeing them together, which makes me feel upset and uncomfortable. When I try to distance myself to protect my feelings, I end up feeling isolated and cut off from my entire social circle.

We have a new years party coming up and i want to go and have fun with my friends but the idea of seeing them makes me upset.

I am doing a combined birthday party in jan with a friend of mine who will want them there but I don’t know if I do. If I don’t invite them I feel comfortable but also feel terrible about leaving them out while every single one of our other friends is invited.

I’ve tried to accept the situation and be supportive, but I still feel weird about it and don’t know how to navigate this without losing friendships or hurting myself emotionally. Any advice would be appreciated.