How do you get over mentally losing your sister (not a physical death)?

My sister treats me like dirt b/c things are not going so well for her right now. She needs a job and wants a divorce. I've been supporting her and her child financially but there are so many incidents where she is just plain awful to me. She'll make ugly comments about me having my 2 kids out of wedlock, but i have a GREAT job and can support them well but she on the other hand gets welfare. And when i try to talk things out with her she'll tell me "you think your allllll that with your fancy job and all". I'm still in my 20s and am to young to be having high blood pressure over this mess. I just need to have her out of my life for my own sanity...how should i do this. Should i turn off her cell phone but keep paying for diapers and stuff (for my nieces sake)? I don't know what to do!!!!