You need to understand that you matter. You're focused entirely on him and how he might feel and/or what he might do. But what about your happiness? Should you just resign yourself to being unhappy?

You have a lot of life left to live. You don't want to spend it miserable. You're not responsible for what might happen to him if you leave. Is he putting the same thought and effort into worrying about your feelings while constantly lying to you? Put that into perspective. Good luck.