To the Op: of course this is hideously painful, which is very likely the motive. He doesn't want full custody of your baby, but he does want you to be in agony because he is vengeful over your affair.
So, while it's probably best to show him and the court, etc. the tearful face, you should also try to be at peace as much as possible in private.
Will he harm your child? No. If he has no history of extreme mental illness and/or violence, the odds that he'd do that are about the same as being struck by falling space debris.
Will he flew the country? Almost certainly not. He can't legally cross the border with her and there are myriad international family law treaties that would allow you to retrieve the baby if he did. If the man is not willing to stay on the run until the baby grows up, it's not likely he will remove that child out of the country.
Presumably you know where he works, so finding him will be simple.
You need a court order awarding you custody and support, and setting out his visitation. Here in the US, what he has done (by tricking you into handing over the baby and refusing to disclose her whereabouts, etc.) would virtually guarantee you will be granted full custody.
You are experiencing terror, which is certainly understandable, but you are almost certainly not actually in great peril and neither is your baby.
My best wishes for your family, and your peace of mind.