Advice ?????

Quick question. These past couple of weeks I’ve been feeling really nostalgic about the past. I’ve been thinking and missing all my old friends and most specifically my ex. It’s been four years since we broke up and/or talked. But it’s not really unusual for me to be thinking about him, I constantly have dreams about him (not sex dreams) and think about him even though it’s been five years. I think I’m over him I mostly just miss the idea of him because I haven’t dated anyone or liked anyone since him. This past couple weeks though I’ve been missing him way more. I’ve been thinking about what might happen if I were to reach out to him or if we were to hang out just to catch up or what not. I cant stop thinking about it. While obsessing over whether or not I should text him I checked to see if he still followed me on instagram and he did not. I still have his number though and snapchat but im not sure what to do. Should I reach out even though it’s been four years or should I just wait for these feelings to retreat? I just want to know if he thinks about me to or if he’s doing well. What do you all think I should do?