Should I leave her alone?

My sister called me and told my family she would be coming down to visit us for the entire spring break. The week of Spring Break she called and said they had dentist appointments and couldn't make it, she would be down the following week. Then a few days later she called and told me her wallet was stolen at CICI Pizza and she didn't know if she could come. I then told her to call and cancel her cards because she was getting an SSI deposit so nobody would withdrawl her money. The next day she was in the bed sleep instead of at the bank handling her business. She avoided my calls and called me told me she would be getting a bus ticket and coming with the girls. She purchased tickets at 9:00am, her tickets were bought and paid for with HER money! At 11:30 I received a text saying she wasn't coming and her daugther had diaraherra. Mind you her tickets are non refundable and once you miss the bus, oh well! The tickets were bought through MEGABUS! Should I leave her alone? My sister has been doing alot of lying and stealing from my mom throughout the years, now its getting worse! I know she has been using Cocaine heavy lately, so do you think I should just live my life and leave her alone? I was looking forward to the visit because I have absolutely no family in Orlando am im very lonely!