I think that you have a right to be near your children, and your children have a right to be able to see you on a regular basis. Here in the States, I have heard that some custody agreements require that ex's live within a certain distance of each other.

It doesn't matter if your ex reacts badly; they are your children as well. She chose to have children with you. Unless there were harm to the children for some reason (and there doesn't seem to be), to be upset that you would want to spend more time with your children, or they with you, would be selfish.

You may also be able to find a job back in France, which would be another positive thing, outside of having more time to spend with your children. I am not married, and have never had children. I can understand, however, how an ex who wasn't very nice to you would make you have reservations about this. But why not look into it, and see what you find out? I don't think it could hurt.