I [21M] had a relationship with my ex-gf [21F] that ended 4 years ago. Can I expect to "recover" at any point in my life?

We were together for 7 months (she was my first girlfriend) and had a mutual break up. A year later we ended up having a friends with benefits arrangement. Yet another year later she started going out with one of my closest friends. Unfortunately this resulted in her being in the back of my mind for well over 2 years and I can't even think about relationships without thinking about her.

TL;DR I can't think about relationships without referring to my first gf, is it fixable? Do I just give it time?