What do you think about my "break-up" letter? Should I send it?

Don't send it. Be strong and confident and move on. Respect yourself. Your letter on the surface says "goodbye", but it has implications that leave the door open. Close it and nevr look back. As you said, "I shouldn't have to beg someone to call me everyday. You should *want* to call me and hang out. " He's not that into you. It happens to everyone. Find someone that deserves you.