Fighting with my son

I am always fighting with my 4 year old boy. I don't blame him, I blame me. Now I just don't know how to fix it. I am a yeller-screamer and now so is he. He tells me he don't like me, he wants to leave and will not listen to a thing I say. When he doesn't I get angry. Stupid I know but I don't know how to handle it. I'm scared I have messed up so bad and have ruined my chances to having a healthy relationship with him. I tell him all the time that mommy is wrong. Spanking doesn't work and if he gets me so angry I will punch a pillow-he see's this. I feel like I am not a good mother and sometimes wish he had a different one so he wasn't in so much pain..... I love my son but am sick and tired of fighting over everything. I'm not saying I want to give my kid away- that would never happen. I just don't know what to do or how to fix myself....