My wife told me she misses her exgirlfriend and I feel so little

My wife told me today that she misses her exgirlfriend and I am not taking it the best. She explained that she misses their friendship. I was around for their friendship era and she (the ex) treated my wife and step kids like shit constantly. She cheated on her while they were dating, stole from her while they were friends, and the last time she saw her tried to physically fight her. I would never imagine treating my family like this. I would never imagine missing anyone who's treated me like this. I understand that feelings are feelings and we can't necessarily help them all of the time. She mentioned some of the things she missed that they would do as friends like going into the woods, and these are things that my wife and I do together and are some of the best moments in my life. I feel like I'm not enough and just want to disappear