Pls give me advice ladies!!

Ok sooo I feel like I’m ruining my relationship because I’m constantly thinking about the past. I feel like I have this anger towards my boyfriends ex and I don’t even know her.. I know that my bf and her lasted three years together and she broke up with him and she was the love of his life.. well his first I’m guessing.. everytime I think about this I get mad at my bf and I shut down.. I just know that I don’t want too loose my bf over this. I do love and care for him but I’m coming to the point that I’m gonna end up leaving this relationship because I’m so brain fu**** right now.