I think in many families there are similar reactions. There certainly was in ours. My sister did not speak to me Fu tbs and accused me of child abuse for taking "her" children away from her!!! My mum ad dad were sad but supportive though my mum is still difficult about the fact we love it here. (she decided not to love it when she came whether she actually did or not!) and Richards mum spent every day of the first 6 months we were here in tears asking us if we had booked our flights home cos she was dying inside!! She then came out to see us, loved it here and is coming again in 2 weeks and again in October!! My sister did get over herself eventually but not before she almost destroyed our relationship with nasty actions we are now almost back to normal after I went back to the uk to see her.
You are not selfish at all to want better things for you and your family. You ate courageous and adventurous and should be praised for giving your family what you think is best. I take my hat off to all who jump into emigrating and I'm sure you will be just fine when the time comes to move.
talk to your sister by what ever media methods available to you anduse your more supportive family members to your advantage for support. Best of luck to you, try not to lose sleep over it, you have enough on without that as well.