Well I would never in hell go back to my ex, I can tell you that.
In fact, I did happen to bump into my ex a few months back with her then-new boyfriend, while they were shopping at my job. Virtually word for word, here's the account of the experience as I described it to my room-mate and his girlfriend:
"kinda caught me off guard; it was around 9 PM I believe.
They were being helped in the Tool section, and that's when she saw me. She smiled at me, and I simply nodded to acknowledge her. She walked over to me (yeah, we didn't see that one coming, right?), said hi and all that.
Obviously convo was about as exciting as it's always been for us. I wished her the best of luck with her new kid; she lied, and told me her Dad was happy about it ( her nephew--my close friend--Tyler told me otherwise). I told her we're doing better with business, going on trips and stuff, and that I'm basically working, and doing business 'round the clock.
I....do think she and her man were trying to put a front on around me, because Tyler has told me that the folks said he's not a very nice guy; I will tell you though he looks like a poor man's version of your buddy (a close friend of my room-mate's).
And yes, she noticed the goatee; she said I looked "different".
She also asked me to re-add her on Facebook to keep in touch, to which I simply responded "I'll think about it" (translation: no way in hell, b!+ch).
I wished them well, and that was it.
I will tell you though: if I had to run into her, I'm glad it was at this point when I'm finally emotionally moving on with my life; it did make it easier.
should I run into her again, I'll thank her for helping me become a better man, and leave it at that.
But yeah, that was the....exciting experience.
Trust me, after the experience, I'm very glad I've moved on with my life.