Struggling with Unresolved Feelings from a Past Relationship

I was seeing this guy for a bit my freshman year of college and I really fell for him and I felt like he did too. Things ended terribly and I was so sad and depressed for about a straight year or two. I tried to apologize twice and talk about what happened and he never said a word. People who I considered my best friends now spend more time with him and his girlfriend than me, while they know how I feel about it. I’ve heard that I need to “deal with it” and that just because he did something to me doesn’t mean they can’t be friends with him. I’m over saying I’m overreacting because my feelings are valid but it’s so frustrating how much it bothers me. Is it because I never got closure and probably never will?