Cheating

My fiancé swears up and down that I cheated on him and that he saw me with his own eyes. I've even taken a lie detector test, he thinks it was fake. He admitted to cheating on me in the summer with two girls. I'm so hurt right now. I didn't cheat on him but he swears that I did. I can't believe he had the nerve to have sex with them in our bed. I plan on staying with him bc I'd like to move past this and we've been together for 4 years now. People make mistakes. I know