What should I do about my professor who insults the Prophet, may God's prayers and peace be upon him, with his comments and describes his exodus from Quraish as treachery, and how should I deal with him if he continues to do so?

Describing the Prophet, peace be upon him, with what the teacher said is a major disbelief that expels one from the fold of Islam. The jurists have deemed anyone who insults a prophet or belittles his right to be an infidel. And whoever insults a prophet or attributes a deficiency to him is an infidel. This person must be advised, and if he persists and does not repent, then he is an infidel, and his case must be reported to the school administration. And it is incumbent upon anyone who attended his lesson and heard him abuse the Prophet, peace be upon him, to immediately respond to him and defend him. If unable, it is obligatory to leave the place, in accordance with the words of Allah Almighty: (And He has already revealed to you in the Book that when you hear the verses of Allah being denied and ridiculed, do not sit with them until they engage in another discourse. Indeed, in that case, you would be like them. Indeed, Allah will gather the hypocrites and disbelievers in Hell all together) [An-Nisa: 140]. And supporting the Prophet, peace be upon him, and defending him is a religious duty, and it is part of revering and honoring him, as Allah Almighty says: (Indeed, We have sent you as a witness and a bringer of good tidings and a warner, that you [believers] may believe in Allah and His Messenger and may honor him and venerate him and exalt Him morning and afternoon) [Al-Fath: 8-9]. So, whoever does not support the Prophet, peace be upon him, is the loser. It is incumbent upon anyone who heard that to defend the Prophet, peace be upon him, and support him.