How do you get over being stupid? ?

I've been called stupid when I was 17 buy a guy I dated when u was 17. It's stuck with me ever since. I feel so stupid and worthless!!! Why am I even here to live? I suck at everything and never seem to succeed. I don't have a learning disability or any disorder. Why am I stupid then? I have a good job, a few good friends, a good degree, a nice home, why am I so stupid? Why do I not catch on to things? Why do I feel so mentally challenged? Is there something wring with me? I was told for years I had disabilities and how I had several disorders, but was never tested and never told by any one except my mother that I was disordered. Why the heck am I this way? I like honestly dint see the point in continuing my life if all my mom is ever gonna think that I'm mentally incapable of life. Why dies she treat me like I'm disabled? Why does she want to hurt me? I don't really wanna ruin the world anymore. I feel like all I do is cause problems and should just die. I'm so sick of myself. Is anyone there?