I would say a quick end to the whole situation is,
HAVE HIM LIVE WITH YOU!!!
You can prove to the court that he resides with you because she threw him out. That why should you be paying child support for him when he lives with you (especially to her) Once that is settled, he can then move out. Once you are taken off the burden of support, your both free to do what you wish.
I am in a very strange situation. My son turned 18 over the summer but I found out that my court order insists that I pay support till he is either 19 or 20 years old. Bad decree indeed! I have petitioned the court to allow me to send the money directly to him without going through his mother (who has never spent on dime on his development).
I need case numbers of cases anywhere in the U.S. that have done this in different states. I went to a court hearing and the judge stated that if I didn’t have any case histories of this being done before, that we would NOT be setting a precedent today- case closed! BAM. I just know that this has been done somewhere before.
As it stands now, the ex throws my son out when it suits her purpose and still is allowed to collect support EVEN WHEN HE DOESN’T reside at her house. He really needs the money to live on and his mother can’t stand to have the gravy train derail. Send any information you might have.