Sorry, My words will be harsh but do try to learn and understand.
You are not his boss. give him freedom. He is with you and you should cherish it. Your happiness should be your love that you love for him not he loves or not. There is nothing like cheating in my eyes. It simply happens. Try to give space to the one whom you love at least. The person who loves you will never leave you n if he leaves and cheats then he does not deserve your caring nature. Be happy for the love you do not for the other It's love. It should be unconditional dear.