Sharing Our Innermost Thoughts

Hello, I really need help with my best friend. First of all I’m an introvert with a very bad social life. I spent most of my life alone with no friends. I donvt have cousins and I didn’t have any friends in my whole middle school years . as a result I have a poor social skills now, and a not so well social life. My friend is an extrovert unlike me, she still doesn’t fit in but she manage to get to know some people and be friend with them.We’ve been friends for more than 4 years. We don’t go out together that much bcz since we graduated high school 2 years ago, each of us was accepted in a different university and I had to move to another city bcz of collage. But we still talked to eachother in a daily basis. The thing is after I finished my finals. And with this quarantine, I really didn’t have much to talk about with her, so couple days or 4 days would pass with out talking to each other. She was mad at me several times bcz I don’t text her and that she feels like i don’t care about her anymore, but the truth is she’s my best and only friend. she means alot to me, she helped me to break alot of my social barriers, she stood with me while I was going through some serious family issues. The reason i doent text her alot like I used to, is bcz during quarentine I have been feeling very negatively about myself, to the point that I literally don’t wanna talk to anyone, even my family. I keep isolating my self for a reasen I don’t know, and when I looked it up at google, it said that it’s bcz ur feeling unworthy and having a low self-esteem, which is something I could relate to, I’ve always had the feeling of I could be replaced, specially that she got new friends at her college, started taking picture with them and play games with them. People who are alot easier to be with, not awkward, makes jokes, comfortable and doesn’t have barriers, absoloutly unlike me. I guess thats why I unintentionally started isolating myself from everyone including her. I wish she shouldn’t take things personally, she told me previously that she got trust issues and always afraid that people will leave her. And i always tell her I wont leave her bcz she is the closest friend I ever had. But thats my way of dealing with my feelings, ISOLATION. but she keep thinking that I would leave her. Last time she got mad at me she told me to constently talk to her or she’ll think I dont care about her anymore. She called me 3 days ago, I didn’t answer. I texed her yesterday apolagising to her but she didn’t text me back. Our friendship is falling apart bcz I don’t know how to deal with neither my feelings nor people. I know I made a huge mistake by not calling her back, and I don’t know how fix things up thats why am asking for help in here…