I changed my mind!
ok, ok, ok, OK. I've calmed down now, read it twice, and I'm going to rationally think about this snape thing. Here is my theory....
I think that Snape isn't really a traitor, I think that Dumbledore made snape promise to do whatever it took to stay a spy to voldermort, just like he made Harry promise to do whatever he said. I think this because
1. All the instances in the other books where Snape helped and/or saved Harry when he all the chances in the world to do harm
2. Snape's answers to Bellatrix's questions in the second chapter were very vague. This is highly out of character for snape. He usually has an answer for every thing.
3. Before he died it said Dumbledore pleaded. Hear that people PLEADED! Dumbledore wouldn't have pleaded if he thought Snape was on the dark side, he wouldn't have given him the satisfaction.
4. There is still the question of what snape "had to do" in book four.
5. Dumbledore said he had a reason to trust snape. I don't think for a minute the only reason was he told about the potters and said he was sorry. Dumbledore isn't that stupid.
6. When Harry and Snape were fighting in the end of the book Snape kept telling him to 'shut your mouth' and wouldn't let him cast an unforgivable. Read it again people. He kept making him stop trying, but never actually hit him. I think knowing what a great dueler snape is if he had actually wanted to hit Harry he could have. Also, when Harry was insulting him he never said anything, UNTIL, Harry called him a coward, then he freaked. I think this is because he was just following through with Dumbledore's orders.
7. Dumbledore would have sacrificed himself without thought for Harry and we all know it.
8. Snape didn't want to take the oath. If he was really on the dark side why would he have hesitated?
There is a glimmer of hope. Faint? Oh god yes, but it's there damn it! And I'm holding on for dear life.
Next post- my prediction for book seven. I know you're all so excited