Child support payment from other relashionship.

My ex boyfriend has a child with another girl. He is always living with them. The whole time we dated, he never told me this. When I got pregnant with him , he told me the truth and abandoned me. I claimed child support 2 months ago and he told the CS department that he pays a huge amount to that child to reduce my child support payment. The CS department called that girl and she said yes. I did not agree so make him go to court next month to show the proof. Will the judge accept the fact that he is living with them but paying child support for them? We live in CA.