Is it my responsibility to enforcing a child support order?

Actually, no. All states have public agencies that seek to enforce child support orders for those who are in need of assistance. These agencies are known as Title IV-D (pronounced "four dee") agencies, after the section of the law that instituted them.

While you will not be on your own, you should be aware that these agencies are often overworked and understaffed, and so your claim may not be addressed for quite some time.