I'm a failure

I have a 2.5 gpa in college and I feel like a failure. I started out college with a 1.27 gpa. Second semester 1.98 gpa. Now at 2.5, like I previously stated. I feel retarded and my brain is nor functioning. Before college, I used to fail the state standardized exam. (1-10th grade) I feel like a complete idiot. My family made fun of me calling me a idiot, loser etc. My dream is to become a doctor, however, I don't feel like I'm smart enough to do that. Alot of people have All A's and I don't. My brother told me when I grow up I should mop floors at my dad's gas-station because I won't be nothing in llife. That happend in 5th grade. My sister called me a "fuING rerd) when I couldn't answer a algebra problem. I do feel like an idot and not smart too.