Why do I feel the way I do?

First step is the "why". I feel that you may not understand the way that you feel. It could be due to childhood issues, past trauma, previous relationships, stress... the list goes on and on. I want you to work on trying to sit there and thinking I am ok. Do you ever ask friends what is going on? Or even framing it as "maybe I am in my head but I feel stuff is off because of x y z." 

I would also encourage you to recognize that rejection, fear, and anxiety. What has contributed for it to impact at such a heavy degree? I would want you to evaluate the friendships. What brought you all together? What do they provide for you, what role do they serve? One key too would be working on trying to recognize who you are. It would make sense to start utilizing positive self talk and trying to build up self-esteem. Maybe spending time with individuals who build you up too. The big focus here is maybe asking questions of friends. You are in charge of your behaviors and responses and if they do things that bug you, make them aware of what they are doing. You are not in charge of how they perceive this. If they are true friends then you should be able to go into a discussion and talking about what changes need to help everyone. 

As odd as this might sound too but trying to work on calming yourself down when recognizing feeling any type of emotions with friends. Yoga, journaling, going on walks, listening to positive music, light exercise. I list all of these because it's finding what works for you. There are other options too but this is where I start. These can help you work on calming yourself down and trying to center yourself and being able to redirect thoughts to more likely rational outcomes. I hope this has provided you with some support. I feel I am never able to fully provide all the thoughts I would like to. I hope you are able to find some support and help down the road. Therapy is a good start.