Betrayed, Don’t let that SOB get away with accusing you of something so horrific as that, that is the worst thing a person could be accused of! This is going to cause you a lot of pain in the future if you don’t find out what is being said about you. I don’t know if it is a good idea to tell Supervisors he is a Sociopath without proof of his behavior?? Most people don’t know what that is, I have only mentioned to a couple people that I trusted I was in a relationship with a S/P I get a “poor her she is crazy look” but, maybe it is just me. Do you have any proof of him harassing you? Emails or texts? Friends or family that could back you up? I wouldn’t go to any supervisors empty handed. They hide so well with their lies and charisma they need to be outted maybe the more victims that out their partners Sociopath awareness will become more widespread.
I am very sorry you are going through this. Be strong!

No, I don't have proof of anything. He did all this underhandedly to get me in trouble. I don't trust anyone. The last few times I volunteered with children, I felt like I was being set up like in "To Catch a Predator".

My emails to him only shows that we were in a relationship. I know he learned my email password and looked through it many times but that's hard to prove.

Thanks for the advice. I am going to continue the volunteering and see what happens.