You are not a coward. I understand how you have come to hate yourself, because I hated myself too when I was lost in addiction, but please know you can help yourself.
As Dee suggested, try a pain clinic to see if you can find some alternative to help you deal with the pain you feel. NA might help you and so might reading our message boards.
In my opinion, it would be very helpful to cut off contact with your mother, at least until a time when you are feeling stronger. The last thing you need is for the person who should be loving and caring to you, to be abusing you.