.Is it legal for a boss to switch you from Salary to Hourly without giving you something in writing

I asked that he provide me documentation and he is refusing stating he doesn't have to when I asked what my new wage is he declined to tell me. My job duties are the same, he is very possessive and is upset because I took a part time job in an unrelated field which does not interfere with this one what so ever he has been cold and purposely picking fights with me since this happened. I have never done anything what so ever on company time for my other employer, This is almost like an absessive husband situation where he feels as if I am cheating on him. ( there has never been any inappropriate interaction between anyone) He has just turned deliberately spiteful and goes out of his way to make my tasks impossible to obtain (such as demanding a 20% increase YOY over last year when industry standard is 3-5% in a good economy.) I have worked with this man for 15 years and only the last 6 months since I started my second job has he acted this way. I simply want an answer as to what the new pay rate is and have it in writing what my new job description is if there is a reduction in pay, am I entitled to this? Please someone help this is getting unbearable.