Can I break my contract with a 90 day rule for resignation if I am being yelled by my boss and I am afraid to go to work?

I am a Nurse Practitioner and I work for a private practice where I do not have an human resource department. I am under a 2 year contract. My boss is the owner and yells and gets in your face when he is angry. I am scared. I turned in my resignation due to breach of our contract by many things including a hostile work environment. He wants to include the 90 day clause. I want to leave before the 90 days.