Crowrido has always been troubled because his magic is very powerful. It is good for a magician to have powerful magic, but it is not good for a person to have magic so powerful that he can predict the future.
So in order to die smoothly, he cut himself into two parts. He thought that all the problems were solved, but when something went beyond his expectation, everything went into chaos.
He wanted to say that he just wanted to rest in peace...