What to do about my mom?

My mom is about 45 years old, single (kicked out my dad after being married 20 years so she could whore around)immature,and i dont know what to do about her. I m 18, and going to move for college once I graduate high school. I want to soend time with my mom, but if she s not at her job where she spends all day on the computer and phone, then she only wants to switch between seats in the house on her phone, talking to her only friend from high school or on facebook. If she s not doing that she s out with one of her many "boyfriends." I make dinner if she doesnt go out to, i clean the house. She gets mad if i try to get her to do something or if i even mention to her doing something that interferes with what she s doing. She wont let me get a job until i graduate or do anything that might interfere with my school stuff, so i cant get a car either, which means i can only sit around the house too. It gets really depressing just sitting here doing nothing all day. She doesnt let me hang out with friends except on weekends sometimes, and doesnt let me go for walks alone even though im 18. If i do it anyway, i get in mega troubke from her, and my dad and grandma so it doesnt seem worth it. I dont know what to do to get out of the house because it gets sad and lonely here.