Of course I couldn't do it right!

H is building some shelves out in the garage. Oh I knew I was going to do a multitude of things wrong when he asked for help. I only had to hold a board level a few times while he drilled some screws in. Well as you can imagine, I certainly couldn't do that without him telling me I was either holding it to tight or not tight enough! Then came the big thing which he explicitly explained to me like I was 10 years old. I was going to have to hold the other end of the board as it came through the electric saw. I was going to have to hold it level with his end or it wouldn't go through. No sh*t! So he goes on one end of to saw and tells me "There's a button on the left". I look and see no button. He repeats "on the left" I keep looking and there's no button. Once again with emphasis he goes "ON THE LEFT!" I scream at him "This is the left and there's NO button!" He goes "My left!" Well why the f**k didn't you say that or "the other left" the first time rather than repeating "on the left" louder 3 times assuming I would get it! The he tells me to hit the button. I see something that looks like a button but it can't be pushed. He rolls his eyes at me as I'm trying to push the button and give me the "oh my god why can't you get this simple thing right" laugh. I then try lifting it up and then it goes. Well it's not a button, it's a lever! Then he just called me out again to help him hold the board. This time he goes off on me saying I need to hold the board up higher and not twist it  because now the cut is all wonky. I'm not twisting the damn board! My god I pull the board and I should be pushing it, I move slow when I should be moving fast. It doesn't matter it's going to be wrong!!Why in the hell does he even ask me to help him when both he and I know I'm not going to do it "right"? I think he assumes that it's such an easy task there's no way I can screw it up. Of course I end up feeling like a total idiot every time.

I  am so tired of being yelled at for the most minor of things! I know damn well if anyone else was helping him he would have said "I mean my left, sorry" in a nice tone. Why does he bully me like that?! And he wonders why his co workers and most people in general don't like him!