I own a local business. Another rival businessman just posted something derrogatory about me on someone I know's Facebook using my first and last name insinuating I had done something which I had not done. It was shown to me by one of my employees who is a Facebook friend of the girl on whose account he posted. This went out to everyone this girl is friends with, many whom are my customers.
I understand he has also been spreading malicious lies at his business about me in attempts to hurt my business. So far I have ignored everything hoping it would go away but it doesn't seem it is going to. I don't really have time or money to file suits but am to the point I have to do something,
What is my best cause of action?

You need to get it all together here, wonderwhy. You don't have to post separate questions https://www.askmehelpdesk.com/criminal-law/how-can-file-perjury-710663.html

If the there are names, and his name is there (otherwise if he is not identified it is just your word it is him), then report him to the police because this is defamation of character on a larger scale then just neighbourhood gossip.He needs to be held accountable.

The police don't handle defamation cases. If you can prove you have suffered a loss do to the defamation, file suit.

I do have it together. These are separate incidents, different people, circumstances and charges. Please see the 2nd answer on this. I agree both or larger than local gossip and both need held accountable but how is that done? I am pretty sure answe 2 is correct. Police don't handle this.

I wasn't inferring that you don't have it together; I meant, together on here.

Scottgem's advise is more appropriate then mine, he is the expert in this instance.

Hire a lawyer and present your information to him.