I find it amazing that everyone seems to be glazing over the fact that your ex kidnapped your child. Yes, she found it easy because you didn't do your due diligence to make sure she did not actually have a live birth. But that bitch stole your kid and knew you wanted to be in its life. That's so shitty I can not see how any reaction you have (short of violence) is not understandable.

You need a lawyer, like 8 years ago yesterday. You don't need a bunch of AH on Reddit telling you that you're a jerk for walking away from a bad situation as soon as you could. Those same people would also say that you dodged a bullet if you told the story of the breakup and "stillbirth" from your perspective.