AITA for not reaching out to my sole remaining family member?

My (f55) sister 57 are the last member of my immediate family. Both parents and our brother have passed. My sis & I are not close but I have recently heard from cousins that she and her daughter and her 3 grandchildren are close to homeless. They live in another state. Since my kids are grown and moved out I have extra room in my house but I don't really want them here. Some background. My sister and I are close in age but she never let me forget that she is the oldest. I have gotten over all the stuff she did to me when we were kids but a few things I am having trouble letting go of. First, when my parents were going on vacation and decided to leave us all at home ( we were all in college) we all made a pact that we would live it up and do whatever while they were away. The only rules my parents left was no parties and no overnight guests.My brother was gone the entire time. Me and my sis had our boyfriends over and played house the entire time. She told on me as soon as they got back and I got kicked out! I couldn't believe she told on me like she wasn't right there with me! I said "Ok..but ask her what she did?" and went to pack. After she cried and cried she finally admitted what she did and they asked her to leave too. But she never actually left and they let her stay. Then on my wedding day she and my Mom came to my fiance's home town and I put them up in a hotel. The plan was for me to go get my hair done early with my SIL and then meet them at the hotel to spend the day together. The ceremony was at 430. I got to the hotel at 820am and they were not there (or just not answering I'm not sure). I stayed in the lobby alone til 245 when they waltz in like nothing was wrong No apology no nothing. Later I discovered the film with pics from the daythat was in my camera bag mysteriously disappeared. I can't say 100% she took it but... There are more things but to the point. I recently found out from a cousin that my sis and her daughter had lost their jobs. My sis supposedly had to have some toes removed due to diabetes. They have not reached out to me at all. However they did contact my DIL to say Hi.....and ask for money. I don't want to reach out to offer help or a place to stay cuz I don't trust either of them. I don't think she loves or even likes me. We don't stay in touch cuz she just talks surface talk and tells half truths (or whole lies) when I call. Not sister stuff at all. No matter how much I try. Should I reach out and let her back into my life?