My 2 year old is spitting at me and saying NO.?

ok i have borderline personaity disorder/bi polar. and my moods are lke crazy. i love my son with all my heart. he is 2. but its lke i cant handle him spitting at me or yelling no when i tell him to do somthing. when he eats dinner he plays with it, throws his food everywhere. writes on the wall. but one min im ok and the next im just all mad. i dont want to take it out on my son. my moods are just crazy. how can i get him to stop getting under my skin. I DONT HIM. never!!! but i yell at him when i get soo upset with him. and he starts crying and then i just want to go somewhere and scream.. i need some advice and help