so if it is all about your son and you believe taking him to court will push your son farther away then what is the question?

why were you contacting him?

if he was going to pay, he would have a long time ago

he isn't

it is just a fact

so

you can take him to court and have him pay
or
not

your son can stay living with him
move in with you
or
live on his own

this isn't about your son

it is about your need to contact your ex