Still having dreams about my ex

So I'm 20, and I was with my ex for three years. We broke up about a year and a half ago. We started dating right before I turned 16. He has still to this day been the only person I've had sex with. I've only been on a couple dates with one person since and it didn't work out. For the first six months or so after we broke up I dreamt of him every night. I still randomly broke down all the time. The dreams were nightmares where I'd be somewhere yelling for him but couldn't find him and I'd wake up in a cold sweat. Or I'd wake up actually feeling like his arms were around me but he wasn't there. These dreams stopped after a few months and I got a little happier. But lately I've just been so numb. The dreams are back. They're different now though. They're just day to day things we'd be doing if we were still together. Random conversation, laying in bed together, at a family event together, etc. It's wigging me out. I thought I was over him. I actually enjoy being single. I'll admit I miss him, but it's more his friendship than anything. We were young when we were together, so we got each other through a lot. I miss my best friend, although I know I could never have anything like that with him. I wouldn't want to. We haven't spoken to/seen each other in almost a year (his choice, I'm blocked on all social media as well) so I can't think of anything that could be triggering these dreams. I hate questioning the fact that I moved on when I was so proud of myself when I thought I had. I don't even know what is normal anymore. I almost never want to date again. He got back out there pretty quickly after we broke up, even though he said he didn't want a relationship. Now all I can do is picture him marrying her one day. I can't stand feeling this pathetic. I feel like I relapsed after moving on.