I also have the same fears as you.
I came to Australia when I was 19 (I'm now 46) as my Mum emigrated over here and remarried. Her parents and Brother also followed but my Nan and Uncle migrated back to England 3 years ago.
My Mum sadly passed away at 56 in 2005 and I went back to England for a holiday to see my Dad,Sister, Aunt and Uncle in Dec 2005. When I was there all. I wanted to do was stay, but I had another life here in Oz. The same feeling again in 2009 when I went back for my Uncle's funeral.
My sister has two sons now and my Dad and Aunty are getting older and although all my adult life is here in Oz, my friends and connections I have to leave. I can't live my life so torn and empty anymore. My family mean everything.
So, I have made the decision and have started the very long list of things that need doing.
Please feel free to Pm me also. I truly feel for how you must be feeling. Either way there is loss hey?
If anyone has any advice or tips please feel free to let me know