Should I ghost my friends?

A couple of days ago I realised how much the people I deemed closest to me, see me as an afterthought. I'm in my second year of college and am about to leave for University after my A-Levels. One of my closest friends at college accidentally let slip that there was a whole college group chat which I was not a part of and then quickly changed the topic. It was then that I realised that this group chat was how all of the circle I was connected to at my college were using to arrange meetups and parties, all of which I had never been invited to a single one. The day after, I saw all my friends post a couple pictures on their story of their night out at a bar, there seemed to be around 20-30 people, most of whom I knew well and talked to a good amount. In the same night, my other friends, accidentally let slip in our group chat that they were going to the pub. And in that moment I realised how truly alone I was. I don't know if it's just my tendancy to isolate, but I feel a deep urge to cut off from them. I was wondering if I am being stupid or if I truly should try and leave.