What do i do with a mom who has cancer and all she does is blame me for everything?

Oh that's so hard! Don't take it so personally! She's facing the possibility of dying! She's stressed, and improperly taking it out on you. But just remember she's the only mom you have, and if she dies you won't be hating her. You'll be sorry if you did. Just keep in mind it's most likely in the end, whether she recovers or dies, she will remember how patient and loving you were, she will be sorry about taking out her stress on you. She's your mom, she loves you, that's a given. No matter how angry she is or mean she seems, just because she gave birth to you and raised you she will always love you forever.