My sister is lying to the father of her children and her new boyfriend, should I tell
My 40yr old sister is has been living with her 2 children and the father of her children (they're not married) for the past 13 years. She's been unhappy with the father for some time because she says he verbally abuses her. He does pay for living expenses. Because of financial reasons she cannot leave the father and move to another place with her children. She claims he knows they're just "roommates" now but he has called me in the past saying he loves her and wonders where she is.
She has been dating another man for the past 6 months and she hasn't told that new man she's still living with the father. She hasn't told the father she dates other men either. She sometimes doesn't come home until 2am and her children have asked in the past why she goes out and why she come home so late.
Recently she came to my mother's house unannounced at 1am, where I was staying the night, with the new man so he wouldn't have to drop her off at her home. She claims she dates him for her own sanity and because she deserves to be happy. I told her she needs to put her children first.
Should I tell her new man or the father the entire truth or is it none of my business?