My question involves child support in the State of: NY

Can a judge change a previous support order to include private school for my 15 year old?

We divorced when he was young and the decree doesn't mention educational expenses. She took me back to court when he was 8 and the judge said I am not obligated to pay private school expenses because I had always objected to her choice of (expensive) religious school which is different than my religion. She remarried a long time ago and has paid his tuition all these years (she has a good income and her husband makes a lot too). This will be his second year at this school and she doesn't want to pay all of it. I can't think of any legal basis for the judge to change the order just because mom wants me to pay. We are going to trial on this pretty soon, no attorneys.