Do you think you will fulfill the criteria to sign on the foreigners register. Requirements are that you prove you have an adequate income and substantial savings?
Have you thought about what would happen if anything happened to your carer? Could you afford to hire someone?What about specialised treatment you may require?
Do you realise what is involved in schooling for your children, and the costs involved, even in a state school?
What if anything happened to you ? your family would be left without free health care, as they are reliant on you.
Why not just enjoy holidays in Spain, without all the stress of a permanent move?