I agree with the others.
She should know that the two of you are communicating (which she does), she should also know the things you talk about in general. No need to give her the intimate details unless she asks.
During one of your conversations with him you might want to ask what is & isn't ok to share with her. ie: it's ok to share things that don't have the word private in the title or first line or something. That doesn't mean you, or he, WILL share those non-private things but it does mean that the world won't end if you 'accidentally' share something.