Is this verbal abuse at work?

A friend I worked with felt it was right to spread rumors about me that weren’t true because I did nothing wrong.

I was his friend. We had a good time, laughed, hung out, etc.
I noticed he was not talking to me. I did not think anything of it because he usually talks to me when I see him.

I knew something was up when he stopped calling me.

In February he broke his silence and told me he was making rumors up about me and another friend. For what reason I had no idea. I asked him to tell my boss and his so it was clear the things being said was not true. He said he did.

May 2016
He started in again. I had 2 people in one day tell me how he was bashing me. I mean real bad. Someone told me he called me a **ch. I looked very perplexed. I broke down in the bathroom and cried. Not understanding where this was coming from.
The other coworker told me he called me ****ole.

I told my boss whatever you said to him, he will not stop. This is stressing me out. I also have a seizure disorder so stress can cause me to have a seizure.

I have no idea what I did to deserve this. Has anyone ever been a victim of verbal abuse at work? How do you deal with the negativity and know it is not true?