File by paper.
Unfortunately, your e-file will continue be rejected because your son has already been claimed. You can file by paper to claim your son. The IRS will then investigate who is the proper person to have claimed your son.
It appears you are the proper person to claim your son. Here is the official criteria:
* be your child (or
adoptive or foster child), sibling, niece, nephew or grandchild;
*
be under age 19, or under age 24 and a full-time student for at least five
months of the year; or be permanently disabled, regardless of age;
* have lived with you for
more than half the year; and
* have provided no more
than half his or her own support for the year.
With your court papers and bank statements, you can easily prove you were the proper person to claim your son.
Your son's father will then have any credits/refunds withdrawn by the IRS with penalties.
I am sorry you are having this difficulty.
