not a functioning member of society

hello. i feel like i cannot function at all. some times i try to wake up with a positive attitude, and for a few hours i feel motivated. but then i am all alone again and i realize it. i can't bring myself to do laundry, so i sleep in dirty sheets. i can't sleep, i can't eat. i'm just not a functioning human being. how do other people do it? how do they stay balanced? how do they eat enough without eating too much? i feel like everything is so black and white. i'm not good enough for anyone. ever since i got cheated on and my bf and i broke up this summer, it's been one bad things after another, one job rejection after another, and nothing i do is good enough. i'm not even worth an explanation, except from my bf, literally: "I don't know why I did it. I just forgot about you in the moment, I was so impressed by her." i want to tear my hair out and go hibernate, but being alone with my thoughts is too difficult. but at least it's better than being around others. it's just too much.