You know the other person probably never gave those special places and or family events the same importance we gave them. They are empty and selfish. They only think about how those places made them feel. Not as a couple or as a family. Remember that.
As for the family meetings. If you were a good person his/ her family will never turn their back on you. I have experienced that with my ex family.
they adore me. Move on. make new memories, for they will erase the bad ones.

I try to have as little contact with my stbx as  I can wether she is with someone else now or not.  The reality of it all is I have to move on because she has, and by limiting our contact I don't have to relive the pain of loosing the person I loved for so many years (getting hurt over and over again).  The last thing I need is to see her with another man.  No one can start the healing process with these in your face reminders day in and day out (at least not in my situation). 

Believe me I know the pain of seeing the ex (or possible ex) with a new person and having them go places that you used to go.  My ex cheated on me with our son's daycare teacher....he wanted out...and we officially divorced 3 months ago.  He is still with this woman.  I have no desire to have him back, but it is so difficult because now she is being integrated into everything that I was a part of.  She is meeting his family, going to places we went, and probably going to the shore next week with him and his family too.  It sucks.....it hurts......and there is nothing I can do about that.  We just need to accept that that is what it is and we need to focus on our own lives and children.  I am currently in a new relationship with a wonderful man.  Things are great, but that does not mean I don't have days that take me back to the family unit that I miss...and that is all that I miss....the family unit...I don't miss him and his cheating heart at all.  I know you are hurting, but try to focus on yourself and your future and happiness.  Dwelling on him and what he is doing with her only hurts you.  Believe me I know it is hard to push it aside, but that is the only way you are going to move forward and you deserve that.  You deserve to be happy.  Good luck!