How do you let memories go, when they've only become a reminder of sadness?

I have gotten a lot of reminders from my "old" life lately. And in many ways, when I hear how they've fallen apart and ruined eachother, I am really happy I got out. But at the same time, I can't help the slightly bitter feeling. Inbetween the constant drama, they talk about how much fun they have, all their adventures and inside jokes, partying and all.

It's mostly fake, do know that. They hate eachothers faces damn much, most of the time.

Having snowballfights on the roof of the mall, doing jumpstyle on the pier and running off to the other side of the fjord without telling a soul.
     Well, that is actually some totally different people. But slightly same thing, they were crazy fuckers and I had such a great time. My first kiss was at this time, my time falling in love and my first time brokenhearted. Oh, the days.

Anyhow... it's not hard for me to see that holding on to memories like this is not very productive. One thin is remembering, but the way I get comfused by the past is far from clever. I need to move on, I really do.

How... to move on, from a past you know so well because you've played reruns over and over in your deepest hour. How, to wake up and finally... deal with, eventually accept, that your life is forever something different?

I don't usually deal with things... I run away and I start over. There is a big difference between that, and dealing with things to move on.

I am right about this, am I not? Or is running away and starting over a good thing? I'm doing it this fall actually... Help me out please.