Hi samdom1
We move out a couple of weeks before you and are experiencing similar things. Some of our friends are in touch more, want to see us more, making the most of the time we have left together. Others are already starting to distance themselves - this goes for family too.
I have been very careful to not discuss our move with people because when we first approached the subject 18 months ago, it went down like a lead balloon! So, we've made sure we've shared information but not gone on and on about our plans and "new life" etc.
I think it's the same with family and friends, they don't know how to deal with it. Some will really miss you, others will think you are selfish, some will be envious, or worse jealous! But we spend our lives evolving and friends will always come and go - it just takes big milestones in your life to find out which ones are true.
As upsetting as it is for you to be experiencing this with old friends who you thought you were close to - you have a huge change coming up and plenty of other things to spend your time thinking and worrying about!