So sorry you are upset OP. This happened to me when my mother called me in error on her mobile whilst talking to my sister on the landline. I felt betrayed and angry at the time but the more I thought about it, I realised our relationship was over anyway because
As well as being negative about me and a situation they were wrong about, they were also guilty of conspiring to defraud council tax. My sister had also conspired with her daughter in her 40s to defraud the benefits system of over £300k.
Her daughter also phoned me, giddy with excitement and said that her then boyfriend was going to bring what was a spurious claim against the NHS - saying a trainee doctor had damaged a nerve in his leg and he would never walk again (he now works full time in a large supermarket!). They were going to spend their ‘winnings’ on holidays.
There are other crimes they are covering up but they are so bad I would need a TW.
My point is this - if they were not ‘family’ and just acquaintances I would have ditched them a long time ago. It took me a while as they are ‘family’ but it was all pretence and it feels so good to be free of them.
I called my sister and told her I had heard every word. She was shocked and even suggested that I might have tapped the phone?! I said no that would be criminal and she was the criminal.
Do tell them you heard - by text if you are not as vocal as me 😊