Need help of unfair dismestle

I was working for a training company for 2 years. I resined do to stress from 4 employees i was the only one left. So had lot of stress on me and desided to resign as all the work was to much for one person. And the boss dont want to employe some one to help me. She gave me a car as n chrismas bonus. And when i resined she told me she want the car back. She is busy to be very agly send me all kind of messesges and say i did work my notice wish i did because of her behavour. So wonder if you can assit me on this. If got messages to prove how agly she is.