Can my ex-husband apply for a green card for his new girlfriend if he is still paying me alimony?

I got a divorce from my husband a few months ago because I found out the was cheating on me with another woman and had a baby with her. My divorce settlement included an alimony because we have been married for 15 years and have two teenage boys. He doesn't make a lot of money (close to minimum wage) so my alimony is very small. Anyways, he now wants to apply for a green card for her because she is an illegal immigrant. I've heard that if a man is paying alimony and doesn't make a lot of money, he can't apply for a green card for others. Is this true? Please help.