I feel bad for you and your children that your best thinking with this horrible and unsafe situation is to wait to get a job in the city where your family and support is, which is a 2 our plane ride away.
I'm not understanding the part where you said, if you were to move now to your mums you'd be giving up your children's financial future. What about their emotional future right now?
You say you have an emergency plan, you say you think about going to the police for restraining order, you mentioned getting cameras and a security system for the home. But no where have you mentioned seeking therapy or counseling for yourself you don't even mention seeking help for domestic violence or pursuing things like that for you. It all seems to lie in the future and all around getting some job down the road. What about today?
Looking at it from way over here, I'd have my a** along with my children on the next plane to my loving and supportive family then worrie about a job.
I'm not judging you, I understand being paralyzed with fear and doing the best you can with what you got. But often the best we got is unhealthy thinking and solutions which lie way down the road based on ifs and when's, that keep us stuck in very unhealthy situations.