My mom and her sister got back together, need help?

In the past my mom and her sister were very close and when her sister's husband went to jail my mom would buy daily household items for her and her children and give them money letting her children stay over our house and buying for them food but when their dad got out of prison he told his family not to talk to us anymore and after afew years later when their house was taken back from the government they want our help now but I can't seem to forgive them and I told my mom that I won't talk to them but my mom insisted me to talk to them what should I do? My mom loan them 150 bucks they pay back and her sister buy for me food and other stuff but whatever they do I can't seem to forgive them cuz I'm thinking that they are just using us again.