Hi OP! You've had a hard time with some of these replies! You are not being unreasonable in not wanting to go. It's a massive change for you!
One thing I want to mention is some friends of ours. They lived in our hometown and were very happy. Both had well paid jobs, but in opposite directions. He was having an extremely long commute though and after they had their first child, decided that they wanted to change something as he was never seeing their daughter. They decided to move to a village very close to where he worked. It meant her giving up her career, which she did because she loved him. He was promising them this amazing family life of having breakfast together, being home for dinner, helping with bedtime, being less stressed, less tired, etc. Sounded perfect and easy because the issues were all down to the commute.
So they moved. She became a SAHM. He kept his promise. All was great. Then the odd night he started having to work later. Then it became every night. Then early starts. Then later on a hobby that took him out of the house for most evenings not long after getting home, plus weekends too. My friend became extremely unhappy. I think she may have even begun drinking too much from messages I received! She was bitter and angry that she gave up everything and now she saw less of him than she was! They also have 3 children now, so her focus really was all on them.
My point is, you could move to the other side of the world for this better job with less stress/hours - but if he is so career driven that he can't switch off, he may not be able to keep that promise to you. So you may be in the exact same position that you are now - but thousands of miles from your home, your current job, your family...... yes you can make new friends, but you cannot replace your mum!
He needs to find a way of proving that things WILL change. If they truly will, then I'd consider going. But if also want to take steps to look into protecting myself and not losing my children if the marriage broke down.
Good luck.