There is more going on here than lying. First of all, there are at least four major things happening, lying is only the way these things are manifesting. There is property destruction, insecurity, mistrust, and acting out against your boyfriend. You are thinking he is cheating on you and checking the hood of his car to prove this to yourself. You are keying his car, a highly expensive and destructive act, and not acknowledging your anger. You are fighting with him and causing a scene when you have created the very reasons for the mistrust. Finally, you want him to trust you, when you haven’t been trustworthy.
This type of behavior tends to come from elements and issues within one’s own personality rather than from the situation. This isn’t about getting your boyfriend to talk to you and to believe you want this to happen and having regret for your actions. That typically is putting the cart before the horse. It won’t do any good to get him tp trust you and believe that you are not going to lie and destroy his property and not make a scene if you don’t work on making that change happen. I wouldn’t try to win him back until you learn how to emotionally self-regulate, and learn about what you are struggling with and how to manage it. Otherwise winning him back has no value.
Here is a test that might help you focus on what may be going on.