Since you are very good at writing, but have problems talking, I suggest that you get pen pals through the Internet or in other ways. Such a friendship can develop to a stage where you eventually meet face-to-face. By then you will already know each other fairly well from email exchanges, and your new friends will know that you have problems talking, and will expect this, so that these problems will not prevent the first face-to-face .
You might consider showing your message to me to your aunt, and ask her to help you to get rid of the harassment from your cousin.
If you look thoroughly, you will find that there are many people with problems who long for friends. They may be shy, fat, old or disabled. Try a first with such a person by writing a nice letter, praising them for something they are good at.
If you have problems talking, then cinema, theatre, sports events and exercise are nice ways to meet. You can go together with a friend, and maybe afterwards discuss what you experienced via the Internet.
I had a patient who had a hearing problem and arrived at psychotherapy deeply depressed. Now he is very interested in art and a member of several art societies. He discusses art with his new friends on the Internet.
A woman who became blind in an accident was also very depressed, but has developed a great interest in music. She often talks on the telephone about music with new friends.
Do not give up. If your first attempts at do not work, struggle on, until you have found the friends you need to be happy.
If you cannot achieve this on your own, a psychotherapist or counselor may be able to help you to overcome this problem. Group therapy is often good for people with problems talking to people, since in group therapy you can exercise talking to people and examine your own aniety about talking to people.