we're here to listen to you. it sounds like things have been tough for a long time, and maybe its time for someone to help shoulder the burden. if you are afraid for yourself and your mother, i think its really important to find someone you can trust and share that information with them. a school counselor is a good place to start, or even a teacher that you feel you can trust. don't try to go at this alone. you shouldn't have to. i am sorry your step-father doesn't seem to appreciate all the good qualities that you have. don't let that change the way you feel about yourself.
if your depression is impacting your ability to function then its time to get help for that. we are all here to listen whenever you need to vent, and please find someone to talk to about whats going on at home. from your message, it sounds as though your stepfather has issues from his own childhood, and getting help for your family might assist him in dealing with his own problems.
stay safe.