Taking minor abroad

I suppose what you need is a guardianship certificate. You would have to file a petition u/s 10 of Guardian & Wards act along with an application u/s 7 of the same act for appointing you as the sole guardian. You would also have to ask for permission of the court for moving the ward out of the courts jurisdiction once your appointment as sole guardian is ordered. Since your husband has not contacted you or the child for 1.5 years the court should Grant you the certificate without any issues plus it's settled law that mother shall have custody of the male child till he attains 7 years of age and puberty in case of a girl child.

YOU HAVE TO FILE A CIVIL SUIT UNDER GUARDIAN AND WARDSHIP ACT FOR THE CUSTODY OF THE CHILD AGAINST YOUR HUSBAND. YOU HAVE TO MENTION THE WRONGS OF YOUR HUSBAND AND YOUR INTEREST TO KEEP THE CHILD. THE COURT AFTER HEARING BOTH PARTIES MAY ALLOW YOUR PETITION. BUT THERE IS CHANCES THAT YOUR HUSBAND MAY GET VISITING RIGHTS AGAINST THE CHILD. UNLESS YOU GET THESE ORDERS YOU CAN'T GO TO FOREIGN COUNTRY WITH THE CHILD.