I never saw that movie, but that doesn't sound right. There's laws and regulations on how cows are supposed to be slaughtered, and if they cut off its legs while alive, it's clearly in violation of that. Temple Grandin (I had to do a paper on her for a class I took on Autism) developed a technique to stun and kill the cow. While many vegans object to it, it's supposed to cause less pain. There may be some places that slaughter animals like that, but they're violating the law.
And organic does not mean treated better. It just means no pesticides nor anti-biotics. So, that may mean that if a cow gets stick, instead of making it better, they just kill it. Or it may mean that they actually treat it better so that it doesn't get sick in the first place. The ONLY way to know whether or not the animals were treated humanely is to go to the farm yourself, which many people are doing now a days.
And obviously you need protein. But there's plenty of protein in beans, nuts, seeds, and whole grains. I eat approximately 1200 calories a day, 1500 on my lifting days (I have issues meeting the calories when I eat homemade food), and STILL get 60g of protein on a vegan diet.
Make the decision for yourself. If you want to eat meat, take responsibility for it. Seek out places that are relatively humane and give them your patronage. If the movie truly affected you that much, you should be motivated to either do that or become vegan. It's up to you.