For months before and after separation I felt guilty and resposnible for my friends and family towards my H. There was a clear rule "nobody talks to him about us". After a while some people said they felt it was their duty to try and talk to him. I refused. Much later when I was relaxed some did without asking me. Later, very many times I thought about it as my way to contol things again. So I let go. Anybody, heck, everybody could talk to him and say whatever if it didn't involve "K told me to tell you this". Very many times I thought I should have let them do it in the first place because he took it as an "embargo" I forced on them. I don't know what is right or wrong. As long as you didn't ask for it, pretend you don't know about. Maybe even, tell him, you had no idea and you hope she didn't make him feel bad and that now you told her she should stay away.