Ok, so I left my husband like 6 months ago and now he is failing with the money he should be giving me for our kids.. What can I do?

He lives in Texas, I live in Mexico now with our kids, he sends me $100 weekly, now, he is starting to fail with that, he is an illegal in USA and I dont want people to be rude with that please, I just need to know what can I do to make him be more punctual with that money, Is there anything I can do? We are married in Mexico by the way..