You have a rather complicated issue here involving both civil and criminal matters. He is civilly liable for paying child support but at the same time you may be criminally liable for statutory rape. You believed him to be 17 when he was really 15. Either way, you knew he was a minor. Also, his family members who knew of your relationship could be likewise criminally liable as accessories and contributing to the delinquency of a minor as they obviously knew his real age even if you didn't yet allowed him to progress with the relationship and even suggested that they had knowledge that you two were sexually involved. Speak with a lawyer. Your ace in the hole could be to press counter-charges against them if they press charges against you for statutory rape. The child support issue is a completely different matter.