@SlartBartFast reading yours reminded me of what my supposed best friend did to me. It was In my teenage years, we were extremely close, always hung out, she always told me how I was her best friend and like a sister. She was the girl at school that no one liked, through me she was able to make friends and people accepted her. Little did I know, the whole time playing bestie with me, she was slandering me to others behind my back, telling complete and utter lies, shared personal matters of course with her vicious twist to it.
She was seeing a boy at the time, he witnessed how sweet she is to my face and a real bitch behind my back. After few months, he rang me and told me everything, I knew he can't be lying as how would he know half the stuff he was telling me and also he has nothing to gain by lying. I then rang her, she admitted it all, I told her I want nothing to do with her anymore, she played the crying card, hung up, she tried calling many times asking for my forgiveness, apparently she did all that because she was jealous of me. There was no way I was going to remain friends or forgive such a cruel human being, I was nothing but a best friend to
Her.
@SlartBartFast
You can confront her without telling her who told you, just refuse to name. If you want to keep the friendship with her dh, then perhaps you'll have to not say anything to her but keep your distance, don't confide in her or tell her any small issues you may have.