Slander? ex post status about how im a slut on fb & myspace?

we have all mutual friends and they all are reading this. What can I do to handle this situation? I broke up with him because he cheated on me and sent a picture of him and the girl to my cell phone. He calls me a slut because I stand up for myself! on fb and myspace he put my first and last name and a bunch of lies about me. Should I sue him for slander or what? He is in the Army...should I let his superiors know about his behavior? and if so how do I do that?