Is there anything I can legally do about someone invading my privacy, going through my personal belongs and spreading rumors about me?

An ex-best friend of mine has been telling false stories about instances where we saw each other after we "broke up." He's making me look like a horrible person but I'm not. I have the exact message he sent to a friend about the instance and it never happened. Now I don't have proof of that, but my story isn't over yet. I have an exact copy of a conversation where he calls inappropriate names, multiple times, and it made me feel horrible about myself. And I have proof that it was me that he was saying it about. Now, this next part is where the question comes in. We work at the same place, and at work we are required to keep our cell phones in the back office. I got a report from a coworker that he went through my phone and went through emails/texts to find out who told me about what he said about me. He is causing me so much distress, and I no longer feel my privacy is safe at work. Is there something that I can do? I want this to stop. He is affecting my life in such a negative way.