Who should I listen to- my friends or girlfriend?

I was bullied by my old group of friends, who I eventually fell out with 5 years ago.

I never see them around and they haven't grown up at all. I have many new friends now.

I saw one of them called Dustin in pub, he tried to call me over but I knew he'd try insult me so I said politely I'm in a rush but to have a good night. As soon as my back was turned he threw a coaster at me.

I got angry and threw it back at him and he got aggressive because I was alone and he was with 6 of his friends, so I felt it best to walk away. 

I met my friend sam outside the pub and told him what happened. We went to the bathroom together 5 minutes later and saw sam in there alone. He said absolutely nothing and avoided looking at me, because he was the one outnumbered and not me (Sam is a good friend who would back me up)

I was tempted to confront him, bit felt he wasn't worth the effort. Sam and my other friend Paul said I should have given him taste of his own medicine by confronting him while I was the one outnumbering him, which they said would put the bad memories to bed once and for all (which had big effect on my confidence for years)

My girlfriend on the other hand was very proud of me when I told her, and said that incident proved I'm better than Dustin and was the bigger man.

Who do you agree with and why?