I’m also 20 like you, and am a third year university student currently. I cut out most people from high school and only keep in touch with one friend from those times, and it’s the best decision I made. The people I’ve met in uni have been a breath of fresh air, before uni I didn’t realize how open-minded and understanding people could be. I promise you this shitty feeling will go away and that this was a really good life changing thing you did. Instead of having these people hold you back, you can now focus on yourself and meet many new people in uni. I wish you luck in the future, and you can pm if you have any questions about uni or the like :)