Relocation: Rules for Relocating With a Child to a New Home, Farther Away

My question involves a child custody case from the State of: texas

i am the mother , i have primary custody of my child , i plan on moving within the state of texas somewhere that is only 48 miles away from the father and i need toknow how much time do i have to give him to be notified of my address change even though im only moving to the next county . i have permission to leave state if i wanted to in my final divorce decree it states that if i intend to move to another state.i have to give him atleast 60 day notice , well i cant find anything that states how long i have if its an instate move . i cant give him a 60 day notive since im moving in two weeks . what is the normal notification period for something like this and what can he do legally if he doesnt like the fact that i moved ...??