Need advice about serious issues in a private boarding school (New York). We are new to the US and don’t know what to do

I too was going to suggest you get counsel from @Hanna . As I understand it, you wish to transfer to another school but are afraid that this school will actively hinder your efforts by providing a poor recommendation.

If your current school did anything for which you have a legal case, you would hope to leverage that to remove that obstacle. Is that right?