Gosh threeangels, a really tough one. I absolutely cannot say 'do this, or do that. I guess I just thought I could empathise a bit.
We moved about 8 hours away from our families a couple of years ago. Only one family member (an aunty) made us feel guilty. Nothing too heavy, just "don't let them forget me!". We have 2 yung children.
The move was great for us,: our quality of life is fantastic complared with what it was in our old home, I adore where I live and feel everything is better here. Everything. I feel like I never want to move from where I am.
But I recently went back for a visit. I feel really bad for my kids missing out on their family. I feel bad for my family too, that I've taken so much away from them (ther're the only grandkids on both sides, and they're not very likely to get any others).
And I also worry about when the parents get old. 1 set of grandparents can't travel as far as us, so they've only seen younger ds twice now ever, so they don't even know him or have a bond with him, which is really sad.
Back to the getting old. I wonder what we will do if/when one of them gets sick - move back when we're really established / put down roots?
It's so difficult.
I don't have the co-dependancy issues that you have, and still the guilt is great.
On the other hand, you can't live you're whole life dissregarding your own needs/ desires.
Plus any help you did receive should have been freely given, and you should not have to spend your whole lives permamently indebted to your mother, even if her help was great.
I guess in your shoes, I probably would make the move, feel really bad about it, but still build a wonderful new life for your family, and try my very hardest to eneble your mum to come over as often as possible.
This may be total drivel, but hopefully at least a little has helped. Good luck with a very tough decision.