Cheater and a manipulator!?

How much trust would you have in your husband if you had to follow him at 4:45am he was supposed to be going to work i caught him behind a bowling alley with a co-worker in her car.he was in the back seat her in the front.But he was caught the evening before by my friend behind another building and they were both in the back seat. and all he can say is they are friends he never cheated on me they are only talking to one another and he.s tired of being accused.