He keeps invading my thoughts

We dated for ten months and he was my first boyfriend plus only guy I’ve been sexually involved with. Sure we had our ups and downs but for the most part I think we were good. Although we were only really together in person for five of the months cause he’s military now. But he decided to break up with me for rather dumb reasons roughly a little over week ago. And I’m over him. But a couple times I tried to masturbate since the breakup and he slips into my mind. I try to quickly remove him from my thoughts when it happens. It’s never for the personality side of him but for the fact he has a extremely nice body and he was decent in bed. But it still feels wrong to think about an ex that I don’t even like anymore. Or does that mean I’m not over him? Is it normal for this to happen? It’s quite weird. I do try to think of other things but my brain usually connects them to him. Does it just go away eventually?