Buddy, it is what it is. Your ex isn’t even worth it to deal with in any humanly possible way.
Probably, only thing left for you in your past “relationship” would be your ultimate liability on your(?) child who should need a lot of prayers and limitless support, whenever/whatever, so that he/she could at least remotely rely on you in your absence. Such a sad sad karma for a poor thing~
You got to stand strong, man!