Hi and thanks for writing JA
I do not know why your mother thinks this is a case for child welfare? I see no case and I work on hundreds of these cases every year.
I see no childhood abuse or negligence from a jerky Dad who uses his child to attract a match online. Shame on him for being such a jerk but then you know that.
I would say before you confront him on his betrayal of you, you get yourself and your child and every thing you need to a safe place and you save every bit of documentation, every personal ad, every shred of email you have on him.
I think you are smart and brave that you know enough to get out and I see absolutely no evidence of child abuse or negligence. It is indeed very cheesy and shameful, but no indication of child abuse.
You take very very good care of yourself and be sure you are safe when you leave him. Call your local womens domestic violence center for help if you need it. Get out and make sure you and your child are in a safe place before you confront him.