he wants my name off deeds and has changed locks ?? can he do this ??

Hi my ex partner and I purchased a house in Spain for 350 000 euros and have spent about 50 000 on building work. We have a mortgage of around 100 000 still owing on this and because I've brought up the children its been my ex who has made all the payments on the house and mortgage. I am on the deeds and the mortgage! He desperately wants me off these deeds and has stopped paying me maintainance in a bullying tactic to try and get me to do this. He hasn't offered me any other deal apart from he will pay me maintainance if i sign over the house .We are non residents of Spain although sometimes his stories are that he is but instead he is on a fantastic wage and dots around 3 countries to avoid paying income tax ! He has changed the locks so myself and my son can't gain entry . Is this legal ??? Can he take my name off the deeds without my consent ?? Is there a way he can force a sale without me ? Is there something else he can do in his bullying that is legal ?? I'm in Spain in April and I'll be greatful for any advice in this matter before then

THANKS