Quoting Tracy B:" That's all you can do, the family will get over it. Does she have children? If yes how would she feel if you kept having a go at hers."
She does not. Her best friend was a single mom and she was in her daughters life pretty much everyday. Her friend let my SIL pretty much talk to her daughter however she liked. Unfortunately a lot of it has carried on with her because she thinks that's okay to talk to my kid like that, but it's not.
Like I said earlier I would totally understand her talking to him if no one was, but if DH and I are handling it, she needs to shut up.
Thanks for the imput ladies. I said I was sorry for snapping, I'll just leave it at that.