from what I gather is that you are not all too happy with this woman, but you do want to be responsible for the child.
The solution is maximization of happiness to all:
You: break with the woman (also "religiously" ) but agree on a monthly (not yearly !..big amounts tend to get spent on luxury items..motocycle,parents expenses, loans to neighbours and what not..) support for the child such that it is guaranteed a proper education and healthcare.
(but ask for receipts.. just to make it difficult for them..).
Agree upon having the right of free visiting your child.
You didn't particularly like the woman anyway. Now you have regained your freedom. (But do live somewhere else!).
She keeps the child (let's face it; there is NO WAY that you can get the child away from her, ESPECIALLY in a country like Indonesia), and gets some financial support from you.
Judging her character I suppose she doesn't care too much about loosing face because of a divorce.
By having a child AND money, she has reached her highest goal in life.
Will have the warmth and attention of a mother for the important first 7 years of his/her life. Will have education and health care thanks to Daddy (of course if there will be another daddy-in-law in the picture, you may decide to stop this support..). And by the time the child reaches 18 or 20 and feel the need to see her/his biological father, then you have no problem with receiving her/him.
If it is to ask for support for a higher education, you 'll be willing to do so. If it is for a new motorcycle and an appartment in Jakarta, then you know the bitchy genes of the mother have won over your genes and you can close the door.
PS legal-the law-illegal..in Indonesia things like that do not matter, what matters is money, and contacts.
I guess you have money and that family don't ?
If you as a foreigner work and live in Indonesia eternally then you may consider the following illegal but common practice:
Disappear to another location, find another woman or nanny and abduct the child at a certain moment under the pretences that that family can not take care of your child (after all it is YOUR child too).
Exclamating that the mother is a hooker, has aids, and her parents have financial problems (they always do).
Before anyone can react jump in the car and whisk off.
Police won't help her because they are not spending enough money on the police.
Should the police have the resources and intelligence and perseverence ( W)(totally unlikely) to look you up on your workplace then explain calmly that you are the father and that only a court order can have the child being taken away and that the mother IS a hooker and have aids...and pay the officers 100 USD.
well, insofar they are poor and decent people..
Going to court is too expensive and takes too long.
So that is Ok.
But.. your new girlfriend must like to take care of that child (a nanny is better)., and the ex should not be thinking of hiring criminals to kill you..
Should that idea arise then you can bluff it by stating that you can hire more and deadlier criminals...but this is up to you to assess...
But leaving indonesia with the child now is impossible.
(except this US thing might help.. but not legally;
at the airport they ask for written /signed agreement of the mother to have you fly with the baby..only if you fake this paper, could this work... the legal way is go to court and have the now US baby assigned to you ...well, forget that..).