Me (21 M) feels like I am in an abusive friendship (20 M)

This is my first post so I hope I am directing it to the correct section.

The title says it all. I became friends with someone when I was in 5th grade and I was in a very difficult spot at that time. We are still friends today and we both are in college. Over the years I have seen him grow and he has seen me too. He has always been straightforward and strict when it came to me. It made me feel insecure and bad about myself (than the self loath I usually have). I don't have many friends and he does have quite a lot. He is a gamer (serious) whereas I play games to spend time with him (I am a musician).

As time passed by I gave him importance every time and thought highly of him. When I make mistakes he gets angry, he starts shouting at me, CAPS LOCKING (during texts) and abuses me. When he makes any mistakes there is no sign of him apologizing but excepts me to forgive him (or not) which I do. It hurts to see someone I admire never cares much for me. I wish he could share all his worries and problems but he doesn't. You’d think by now we would share our friendship in a more pure manner but overtime I just start to hate and get angrier at myself for tolerating him. My mother has repeatedly told me OVER and OVER again to cut all ties with him and throw him away like trash since he treats you like one. I never listen, because I don’t have anyone else to share my feelings with and spend time. All my friends who I have come to known, over the course of a few months start being distant and forgetting me.

You can all say, “Well, follow what your mother says.”. But it doesn’t work like that. I can’t stand up for myself because I’m too afraid. I have social anxiety and my life hasn’t been all easy like he has it. He tells me that I will never change and I will always be the same, that I am prone to have problems with the behavior I have. But I cannot change. I am sensitive, maybe a bit, but I am stronger at heart. I would like some advice, some strong yet caring words.

tl:dr Have a friend since 5th grade, feel abused as he is always mean, need some advice because I cannot stand up for myself since I am afraid of losing the only friend I have left.