Do I need a lawyer?

[CS250]

I was working for a so called "friend" until I was accused of stealing money, which was in the office and given to him on that day. ($800) I quit that same day, which was a few months ago, like Oct. I was being paid under the table, he would sign a check and I would write it out for my hours. I never received any tax forms at the end of 2007 nor did I sign a W-4 or 1099 form for employment, ever. This went on for about a year and a half. He is now, in Jan., accusing me of stealing over $20,000 in cash, which I did not do. He was taking cash and living off of it because he did not have a job. He is also disputing what he was paying me. Nothing was ever questioned until now. I worked with his accountant, who apparently has passed away, and did everything the way I was told and taught. He is threatening to file charges against me, but I am not sure what for, or even what kind of files can be charged against me. Please help!