I think it helps to not always dwell on the negative, it will drive you crazy. Maybe you can use all your free time to learn about something thats on your mind? That the glass is half full instead of half empty theory that i try to think about when im really bored, doesnt always work though aye.
I think joining clubs are an excellent idea for getting out and about, like something your really interested in, a chess club or something. Ive done that myself and now im more looking for free time to do stuff! Im committed to being somewhere 3 times a week. Its really hard when you think everyone is evil and hates you but at the place i go i know that im super reserved, shy, very anxious, weird but i have had no bad experiences, im thinking its amazing how accepting people can be.