If man thought child was his at the time of birth but no paternity tst was done, signed birth cert paid cheating ex GF csh 4 daycr 4 yrs rights arearg

Nick dating woman 4 years while he was working she was cheating no paternity test done yet he signed birth certificate he has paid for medical daycare but all thru cash to mom and day care judge issued child support with arrearages without considering what he did pay with witnesses including daycare in florida he now has been ordered to pay back child support from birth even though she didn't file for child support until 7 months ago when he wanted more visitations which she has refused or promised to do so then no shows even on holidays. As I stated she stated she made so much income wouldn't a judge figure out she couldn't have paid all bills she claimed on what she stated she earned and still no paternity test has ever been done. She cheated for ever what if he;s not the father? Why will DCF help her for free but not him? She has state attny thru DCF and he can't afford lawyer with as little as he makes with paying child support plus arrearages at 40K Grs not net DCF won't help him