Is there any civilized way to tell off his obsessive ex-girlfriend?

STAY AWAY! I was in a similar experience and I told my bf at the time that I wanted nothing to do with her. If he continued to communicate with her in any way I was going to dump him. She will never get a life, and will never get over him. THAT IS NOT HIS PROBLEM. What your boyfriend should be concerned about is how you feel. if you are uncomfortable with all this, Tell him he needs to fix up his baggage. He needs to man up and talk to her straight, regardless if she knows all his secrets. If she is going to be a *&@! then she's going to be a *&@!. You're only hope is that your bf can drop her like a hot rock, and tell her to f*** off. If she goes around telling all his secrets, then she does and that's some thing he has to live with b/c he made that choice. He shouldn't let his past affect your present relationship, and the fact that it has gone on like this is worrisome. Tell your bf straight up that its do or die time- tell his ex to get lost or you'll become his next ex.