Why am I so lonely?

I’ve never had a problem with friends before, I’ve always had a friendship group to rely on. But after a falling out with my toxic ex best friend I have found it so hard to find a new close friend. I have lots of other people that I talk to in class but I have noticed that when I’m trying to reach out and get closer to people they shut me off and exclude me. It’s hurting my self esteem so much and I’m so embarrassed of myself, please help !!! 😪