did I do the right thing?...

Thanks to all who gave me words of encouragement on my previous post...I will try hard to learn from those who are more aware than I of this sickness....
Wondering if I am doing the right thing...looking for advice I guess...
Yesterday I ran into my exN (only 10 days ex)....in Walmart...I saw him when I entered the store...he was at the registers...I was getting work supplies...and couldn't just walk out...figured he would go thru the line and leave...I saw him look my way....I put my head down and just continued on my way...He came to where I was...stood there...and said "Uh...Hello?..."....the last time we had had contact...I had found him in a bar with a girl(who is probably as ignorant as I thinking "she" is his girlfriend too)....when confronted...walked out...and has ignored any attempt of contact from me....(I tried to talk to him for about 36 hours after the incident...and haven't since then)
I turned my head and walked on by....
Was that the correct thing to do? Do I act like he doesn't exist? Or do I politely say hi...then move on...
Not sure what is the right thing to do....being polite may keep him from revenge on me is my thinking...
But my thinking isn't too great right now...
So any advice would be welcome...
thx again...=]