Statistics unfortunately show that a partner who cheats several times will rarely stop. It's concerning that not only is your boyfriend being unfaithful to you, but that he is now making you out to be the "bad guy" for not trusting him. My advice would be for you to seriously consider your reasons for remaining in this relationship. I understand that this must be extremely confusing and upsetting for you. Perhaps seeking face to face help from a professional would help you to get your thoughts and priorities in order.