Should I stay with him?

Personally, it sounds like things are moving a little too fast especially if you are still in school and under 21. If you don't even know the status of your relationship-it should be your first concern before you even think about moving in together. Make sure you know where you both stand in the relationship before you take it to the next level. Also, if he's already being a jerk to you and it's only been a month how do you think he will be a year or five years from now?