here's my experience Bob.....
Five years ago i made the decision to leave, within 6 months i started to think i'd made a mistake...within a year i knew it.
At the time i too was getting sick of the difficulties of trying to live/work in a place where i would always essentially be an outsider, i was desperately missing my family and my culture, so i sold up and left.
The problem turned out to be that the country i thought i was going back to was just a figment of my imagination, things had changed massively and i ended up feeling more of an outsider here than in Thailand.
I had completely forgotten the reasons why i left the UK in the first place and the rose tinted memories i had were just a pipe dream really.
I had also got to the point where all of the amazing things about living in Thailand had just become normal, all the things that people love when they come to Thailand were just my everyday life, i had forgotten how amazing that was.
I desperately miss my life in Thailand and i think about it every single day often accompanied by tears.
My advice would be if you do decide to leave DON'T be so final about it, maybe go back for a few month's and the reassess how you feel before you cut all ties.
Good luck.