Being around the N XBF Again-How to act?

OK heres a quick overview of the story:

Me and XN met at a bar I like to go to. We dated for a few months, has the usual problems (him flirting, hot n cold, pushing me away ect) I confronted him with a big klie I busted him in, then he immediately publicly dumped me and ran a 'shes a psycho' smear campaign, humilitaing the heck out of me in front of all my friends. He pitted me and his HPD BFF in a fight the night I got D+D'd, I beat her a$$ and ended up getting thrown out. Well, it has been a year since all this occured. He moved on to new NS, and shes a barmaid there.

I am dating someone that me and the N both know, who also frequents the bar, (I met him before the N)and since the the HPD I beat up got fired for her HPD antics last week, I have been 'granted permission to come back'...lol.

XN still goes there to visit his NS, as I said she works there. Hes not there very often anymore, since a lot of people have caught on that something is 'off' with him and that he's a liar. I have a feeling he will disappear, as he can no longer control the situation there with his HPD friend gone, but, any advice on how to act when I do eventually run into him? And the new NS. I would like to go and enjoy myslef, without getting sucked in to any more of the drama, or feeding him any further supply. I will be there with my new BF-the N wont even speak to him, BTW.

Oh crap....this was supposed to go on the narc forum....lol...sorry.