Amadeus play: what happens to Mozart at the end of Amadeus?

I have to do a narrative in English based on the play "Amadeus" and the scene that I'm going to do is a bit towards the end of the play where Constanze thinks that Mozart is going crazy but I was reading and cannot figure out why Mozart has gone crazy. If you could answer this asap, i would really appreciate it. Also, I need serious answers please because this is for an ignment.