I live in Virginia. I'm a casemanager at a homeless shelter and my supervisor has on more than one ocassion put me in an extremely uncomfortable position. He told one guy that I called him a crackhead and to look out for me because I was out to get him. He has told other clients I am mentally unstable and have been in a psych ward. After bringing this to the executive director's attention, she issued a memo we all had to sign about such issues and if the behavior didn't stop the guilty party(ies) would be terminated. Well, needless to say it hasn't stopped and I went to her again and she said to prove it. Being that these are homeless people, I can't and won't track them down, however, there is still one in house that things have been said to about me. Can I quit and get unemployment based on slander and defamation?

prove it.

that's how "slander & defamation" goes.

Unemployment is in general if you separated from employment by no fault of your own. Usually if you quit you don't get it, unless you have a very compelling reason for doing so. I do not know, but think it is unlikely, that this would qualify.

If you feel that this may, now or in the future cause serious harm to your reputation in your profession, then take your bosses advice and
Prove it.

Check with state laws on tape recording. Issue a letter to your supervisor outlining what was said by whom (you will need witnesses, like it or lump it) and POLITELY ask him not to say such things.

Defamation is EXTREMELY difficult to prove. You need to PROVE that what the person is saying was not only FALSE, but that they KNEW it was false and stated this maliciously, anyway. they can say they were just mistaken. They can state their opinion. Moreover, even if you get past THAT step, you have to PROVE that you suffered economic damages. Like, refused a job offer.

Sending a letter & "proving it" just to your boss may at least help resolve things internally. If it escallates into this person giving you bad reviews so that you are FIRED. THEN you will have a paper & people trail showing that the person violated the new policy & you made efforts to resolve.
Then you might get unemployment.
good luck to you.