OP, calm down. You are slowly edging to being an adult, when you have to deal with unfair situations all the time. This is not the end of your career, even if your advisor refuses to write you a letter of recommendation. Actually, if you have publishable data and are going to be one of the authors, your advisor will most likely speak well of you professionally because the quality of your work (and you as a person) will reflect back on his mentoring.
Now, that being said, you should definitely schedule a sit down meeting with him, and as someone else said, speak frankly. Be HUMBLE. I cannot stress this enough. No matter what you think, the fact that he wrote "we can talk about this when I return" is a positive sign that your relationship can be salvaged. It is not an "F you" signal. If he really just wanted to do that, he would not have bothered to invite you to talk with him; PI's have many time-consuming and stressful things so meeting with them is a privilege. Do not use the attitude that you have here in your posts: a combination of self-righteousness, hysteria, and indignation. While those feelings may or may not be warranted, all they will do is harm you further in your interactions with your PI.
Ultimately, the evaluation that is stressing you out is for your eyes only, and the only thing that adcom's will see is your final grade in the class and your thesis advisor's letter of recommendation if he writes you one. In fact, even your final grade isn't that important as long as you repair your relations and have a good letter. If you really do impress him in the next few weeks, he can always say in his letter "I gave him a bad grade, but he was actually an outstanding lab contributor and I would change the grade if I could."
Not having a letter from your advisor is a big red flag if you want to get into an MD-PhD program, which is why you should do everything possible to salvage your relationship. But again, even if you don't get a letter from him, you will still be able to get into grad/med schools if you explain your situation to your academic dean or whoever is writing your committee letter. It will just be a harder road, which is why you need to do all you can to repair relations.
Take home message: be humble, acknowledge your mistakes (and don't try to pin blame on him, even if it's deserved because doing that won't help you in any way), ask what you can do to help publish the data, and move on. Good luck.
