A Little Bit of Venting (feel free to ignore but I need to vent)

Ok I am sick and tired of my manager telling me I'm worthless and that I don't know how to do my job. Yesterday, I opened up the kitchen and I was ahead of schedule on everything and so I figured I would get a little extra work done that has been needed done for a couple of months now; you know our deep cleaning like washing the walls and vents and organizing the filing cabinet. Well, when my manager came in the first thing he did was get on my case for not having our cold to go meals out. now You should know our cold to go meals take about an hour to make because we have to chill them for about 45 minutes befaroe we can put them out for the public. Well when he came in they were in the blast chiller and before I could tell him that he got on me for something that I never did and that isn't in my job description. He got mad at me for not going to the morning meeting. Well the thing is I'm not allowed in the morning meeting with all the other departments because its for the manager not the assistant manager. The only exception that I would get to that is when he goes in for surgery and then he'll be gone and I will take over for him while he's gone.
Then he goes and complains to the store managers that I'm not doing my job and that its my fault that we're losing sales when in actuality its his fault! This is true, I have several customers come up to me and ask who cooked today and if it's Dat who cooked they won't buy anything. His food tastes like burnt rubber no matter what dish it is. He is just so mean and nasty towards me. Of course when the store managers are around he's the perfect employee but the moment that they're gone he turns back into a monster. I swear he's bipolar. And no matter how many times that I complain about him or any of the other employees complain about him our complaints go on deaf ears and we get written up for his mistakes. I'm sick and tired of it. It got so bad yesterday that at 5 pm I went upstairs to the store managers and told them flat out I was leaving for the day (there were 3 others there so I didn't leave hanging) and that if Dat ever puts me down or critisizes me personally again I was leaving without any notice. They said that they would talk to Dat but since working with him today he was just about as bad as he was yesterday. I went home crying last night, it was that bad. I'm sick of the crap that goes on. If the company would notice that since Dat has been here only four of us employees have lasted more than a year. Everyone else just leaves because they don't want to put up with his crap. The sad part is that if I didn't need this job I would've left ages ago.