Retroactive Jealousy

Recently I have been very hard on myself, due to some recent life changes and things I see as “failure”. Along with this I have become obsessed with my current boyfriends ex girlfriend. I barely know anything about her-I think I know her name- but I do know they were together for about 4 years. We have been together for 2, and I can’t help but think about their relationship all the time. I know it’s irrational, and I have NOTHING to worry about, but my self-doubt keeps creeping in, and I can’t stop obsessing. Has anyone been through the same thing, and if so, how have you dealt with it? I feel like telling him about it might help clear the air, however I am also concerned I’ll look jealous, which I absolutely do not want to do.