AIO for feeling hurt that my best friend might be dating my former best friend without telling me?

So I (16M) had a best friend, I’ll call him Dave. We were incredibly close, but around 9 months ago we had a falling out. Since then, we’ve only spoken when absolutely necessary, and even then it’s been very minimal.

Honestly, that friendship breakup was one of the hardest things I’ve gone through. I don’t have many close male friends because I’m not really the stereotypical straight guy—I’m more feminine and outgoing—so losing that friendship hit me really hard.

During all of this, my other best friend, who I’ll call Sarah, was there for me. We’ve been close since 7th grade, and she really helped me get through everything. I’d tell her how much I missed Dave, ask whether I should reach out, and she’d give me advice about what to do or whether she thought it was a good time to talk to him.

Earlier today, Sarah and I were hanging out at a café. She left her iPad at the table while she went to order. I asked if I could use it to watch TikTok, and she said yes.

While scrolling, I found a video I wanted to send to myself. When I hit the share button, I noticed Dave’s account in the recommended list.

That alone wouldn’t have bothered me, but on TikTok, someone usually appears there if you interact with them often or if they’re pinned in your messages. Out of curiosity, I opened the messages tab, and sure enough, Dave was pinned.

That’s when I remembered something that had been in the back of my mind for a while. I once asked another close friend if Sarah was seeing anyone because I had a feeling something was going on. She told me Sarah was in a relationship but didn’t know with whom.

On top of that, Dave’s TikTok display name was something like “Davey,” which made me wonder if it was actually him.

Now I’m wondering if Sarah and Dave have been dating this whole time and just never told me. Sarah knows how devastated I was after my friendship with Dave changed. She knows how often I talked about him, how much I missed what we had, and that I still cared about him even after our falling out.

I’m not upset because they might be dating. They can date whoever they want. What hurts is the possibility that one of my closest friends has been hiding something this significant from me while also comforting me through losing that friendship. I’m also worried everyone else in our friend group already knows and I’m the only one left out.

I haven’t confronted Sarah because I don’t actually know if they’re together, and I don’t want to accuse anyone based on a pinned chat and a few suspicions.
Am I overreacting for feeling hurt and left out?