What would you do in this situation? He loves us equally doesn’t he?

Doubt anyone here wants to give advice on 15 year olds’ polyamorous relationships

I’m sorry to hear that. You are not overreacting but I’m sure he feels the same about you two :)

I’ve never been in a poly relationship, but from the ones I’ve seen I think the key is to distribute your affections between partners in proportion to the affection they’re willing to devote to you. In general this distribution won’t be equal, nor will it match what any given partner would want it to be in a perfect world. If everyone isn’t willing to accept that, it’s not likely to end well.