How do I tell my crush/bf that I don't like him anymore?

You need to call him and express your feelings, because to just leave him by himself wondering about what you are doing or what's going on isn't fair at all. I mean you are a nice girl, I'm assuming, and you said he is a jerk, not telling him anything, is basically like being a jerk. Just talk to him, let him know whats up and everything will work out from there.