Why is my ex husband taunting me? HELP!?

long story short, my ex husband abandoned our family to be with an older woman. He knows that I was waiting to graduate school to move to georgia to better my job opportunity in my new career field. I have an apartment there, utilities cut on already, childcare, schools, etc. There was already a custody agreement in place, saying that I am my son's primary custodial parent, and my ex has visitation only. His girlfriend also abused my son and there was a cyf investigation. He waited till I am ready to move to file for weekend visitation, knowing that is going to hold me up, saying, I'll just keep you here longer til this is over. Why would he want to hold me up like this? Why would he wait till now to file for visitation, knowing there was already a custody order in place and he never followed it? He never calls or sees the children. I have a better job opportunity in GA and I really don't want to seperate my two children. Any advice? He also doesn't have his own residence, he lives with his girlfriend in government housing.