being accused and abused at work, what do I do?

[Justin]

ok i have worked at a company for almost 4 years, have always had praise from my co-workers, bosses, and customers about my nice personality, and great work that i do. i take pride in my work, and have always made it a point to do everything my position asks of me and then some, and i have always made sure to be courteous to everyone no matter how i am feeling. i work with the public, and they love to complain. many of my co-workers have had complaints because you just cant please everyone these days right? well i have never had a complaint, never had any type of problem of any sort at work with anyone. well my boss says all the sudden today "we need to have a meeting" so i'm like ok, i'm a little confused but i go ahead and fallow her into the meeting room, and in the room is my bosses boss. so its me, my boss and her boss. they both just drop their smiles and start asking me whats going on with my co workers, saying i have been mistreating one of my co workers, even went to the point and saying i have been racially profiling a co worker and mistreating them because of their race. which is insane, i am of mixed race my self. I have never in any way mistreated a co worker or treated any of my co workers differently. they both said they have noticed a change in my work and attitude, and honestly there has been no change. I told them no, that's not true, i have not treated anyone wrongly, and they both interrupted me and said "yes you have" finally after interrogating me for 45 minutes they bring in the accusing co worker, and ask her to tell me what i have done to make her feel uncomfortable, and she just straight out began to lie, saying i have mistreated her, said things to her, treated her badly, and on and on. the bosses both tell me they are VERY disappointed in me, and no matter how much i defend myself, they say "no" as if nothing i say means anything! after 70 minutes of this i was in tears, i've never been wrongly accused, never had 3 people against me in a room, accusing me of something i clearly am not guilty of. what should i do, i am scared to back to work, i feel sad and cant sleep. should i make complaint on the company? should i do nothing and let them continue to abuse me? should i contact a lawyer?