I was once in a similar situation but this is what made me take action. I was in a casual conversation with two, male Doctors. They knew I was a single mom and asked about child support. When I said it was more important that my daughter have a good relationship with their dad, this is what they asked me:

Do you believe that as a parent it is your responsibility to provide the best possible life for your child? Of course I answered, yes.

Don't you think your children would have a better life if you could afford better accomodations, better food and access to higher education? Of course, I said.

Don't you think, therefore, that it is your responsibility to pursue child support through the courts?

Well, if you put it that way...

Smartest thing I ever did. The court gave me twice as much as I asked for. He didn't leave the country or avoid his responsibility. He simply paid every month. He became a responsible parent because he was forced to be accountable. Did it ruin his relationship with his children? No, it strengthened it.

Now that they are grown, they have respect for him. I doubt that would have happened if I had allowed him to be a deadbeat.