How Can I Report Someone Faking Their Disability?

I honestly need help with this because I don't know how to go about this. My mom has a mental disorder, but no she's not the one faking it. It's her 'boyfriend' I can't really say it's a boyfriend because he cheats on her on a daily basis and has even taken it as far as getting TWO girls pregnant. This was when they were married, there now divorced but I'm rambling here. The problem now is that he's faking "Schizophrenia" there is NOTHING wrong with this man, he's been around for 11 years so I know there is no mental disorder with him he doesn't pay child support, nor does he want a job. He chooses to sell pills and coke, he even does them. Every-time I come home he likes too talk loudly how he's getting his check. 2,000 a month to be exact after talking with his lawyers and such. At first I thought he was lying but my mother confirmed it. How do I go about reporting this? I know this isn't something I can 'prove'.He even told me how he purposely goes to the Harbor so he can fake something wrong with him. It's unfair a person like this should be getting disability. It's just something there trying to get so they don't have to work and continue to be a abusive moocher.