i don't feel like doing anything anymore?

people made mistake , i work hard each day to correct those mistake in the pass ( financially ) so my mom can have a home , her business back and live a nice elder life. my sister however recently just came in to the picture and demanded her name to be on everything , a house i plan to buy with my mom , a co owner of our business that when we first started a decade ago she said it's gonna fail and moved out and only came and help us when it picked up couple years ago, when my mom was hospitalized my sis was no where to be found , when my mom filed the bankruptcy eventhough i hired a lawyer i did all the paperwork also when she did shortsale at our old house many years as well , recently my sis fired one of the waitress eventhough she's not the owner and i just found out about it , the thing is i dont want to worry my mom so i try to get along with her but she is just selfish , now i dont feel like going to work , i dont want to buy a house for my mom anymore knowing my sister is just waiting for her to die and inherit everything i and her worked hard for , im just burnt out. as if it doesnnt matter what i do in the end she will take it all , i know my sis she will backstab me the sec i screw up , i just dont trust her but a mother could never abandon her child so im just freaking depress