He’s going to keep threatening the joint custody thing and controlling the maintenance. I was in the same situation for 5 years when i decided enough was enough and contacted child maintenance and took my ex to court to put an official agreement in place. Due to his job and the fact your ex is not around all the time i would think the chances of him currently getting joint custody would be pretty slim. If he’s not willing to negotiate the only thing you can do is carry on as you are or call his bluff and tell him to take you to court, you’ll have to attend mediation first. it is scary but in my case it was worth doing.