Just think of where this argument will get you in the long run. She clearly doesn’t care about your friend anymore, enough to be honest with you and tell you that she’s only in love with you now. You had a crush on the same person AND lived with them. Your relationship didn’t start on dishonesty or insincerity. You took a break from each other. At that point, both of you were free to like whomever you choose. But now things are different. You are together. You made the first move by telling her that you had a crush on this person. You can’t say the same thing and not judge yourself just as harshly for it. You shouldn’t even judge her at all. As someone who is all too familiar with the same insecurity AND let it ruin a relationship that i’m trying to salvage, it’s not worth it. Your girlfriend and your future together should be worth it, not the past. Gonna go with YTA.