I don't think any man should try to stop you seeing your family. He knew you had children when you got together but maybe not having a family of his own he possibly didn't appreciate the strength of those ties. It's sad that he is making it a them or him situation. I think you would end up resenting him if you were to move away and you'd miss your family dreadfully. Would you be able to travel back regularly to see them or is he expecting you to cut yourself off? He doesn't sound like much of a team player. To buy a house secretly is pretty calculated. I don't think you should have to choose but the situation is of his making not yours and you shouldn't be guilt tripped into a decision that you are not comfortable with.
Do you still wear you original wedding and engagement ring