did I do the right thing?

Okay basically I was talking to one of my friends about my current boyfriend and my friend had dated this boy that I'm with and she knows his paswords to everything and she said to me have you been on ...'s Facebook messenger I said no she said oh I have I go on it all the time I read all his messages even the ones to you and at this point I'm so angry and she's read all the recent ones and I told him he's really mad at her because I tell him private things and he's the only one that knows about these things and she knows everything and she's the sort of girl to screenshot messages and idk if I have done the right thing by telling him I feel really upst tbh