If your friends knew the extent of what happened, I am pretty sure your ex would no longer be a problem at events of mutual friends, because they'd likely decide that what he did, and the kind of person who does that, is not welcome in their lives. Why should YOU keep yourself from friends because of what someone else did that no-one would be ok with? Does that make sense?
Of course, all of this takes time, and I hope that from this thread and with a counsellor that you can find a time and way to let your friends in on HIS dirty secret, strip him of his power and continued control of your emotions and current relationship, and get the support from people around you. Our support here in BB is a given that you can take for granted IRL support is what you'll need as well - IRL hugs are better, too.
You are so on the right track - just by writing it out shows YOU that you are ready to make this better, to give it a name and to give it a compartment. You know what they say - germs die when you get some sunlight on them xxx