How do I get back child support if husband went to Mexico?

My husband and I have been married for 35 years. But during these 35 years, we have separated more than 10 times. I have 2 children from a previous marriage and 2 more children from my 2nd marriage. This whole issue of child support and receiving cash aid is very confusing to me. I worked off and on thru out my marriage and at the same time I was having marital problems which caused my husband and I to separate. His income was very low and he would have a difficult time paying the full amount of the court ordered child support payments. But he was paying his child support. With my income and sometimes receiving child support, my husband and I still would have difficulty making ends meet, and I would apply for aid for my 4 children even though 2 children were from my 1st marriage. My 1st husband’s child support was at such a low amount $204 a month and sometimes he would pay and sometimes I would receive $50 only. This entire child support and back arrears are so confusing. The 2 children I have with my second marriage are now 33 and 29 years old. My 2nd husband which we're still together has been paying back child support for more than 30 years. Family support has made a mess out of this whole issue. The very last time my husband and I went to the family support division and spoke with the district attorney who was then opening up another new court ordered for back child support and a new order for child support if for some reason my husband and I separate again, the new court order was raising his court ordered child support payment from $400 to $740. For our then 2 teenage children. At that time, his back arrears on child support on paying back cash aid was close to $13,000. Well my husband had a family emergency. His mother had gotten very ill and she lived in Mexico. My husband left to Mexico immediately to care for his mom and left me and my children without an income. I hadn't worked in 4 years due to raising up my 4 children.