Feel so horrible? Am i a horrible person for this? yelling at my mom because she protects her bad son? :(?

I feel very horrible and ill for being mean to mom but i just cant take the pain anymore. She has a very abusive crazy son who is on probation for drug dealing and when she told me he would come to the house to meet with a "social worker" i started to snap and tell her would you bring him to the house when he did so many horrible things and i cant get forgot what he did and my mom ignores it and is in denial. i started to get so mad that i started to say a lot of things to her like she is crazy and i can never be in peace in this house, i was cursed. Then she started to get ready for work early and told me before she left "i will leave you in peace" that really hurt because i feel so guilty and she still would have been in the house if i did not go crazy :/ i have constant mood swings and anxiety and its gets to the best of me sometimes i dont understand even though she does not want to understand my feelings and acknowledge them and deny what happened, why do i still feel guilty and sad when i may have hurt her when she does not even care about my feelings? its so crazy how she is pretty loving and caring towards me except for this situation. is that why it hurts so much