The end of Lily and Severus's friendship needn't have happend. Snape was under a lot of stress, and it slipped out. HE didn't mean to call her Mooodblood. He loved her, but we all do things under pressure that we would usually do. If you were getting dangled upsidown by your ankle by some bullies, wouldn't you be under stress too? This part always makes me cry, and I always feel bad for both of them. Two best friends ripped apart by a mistake, and the inability to forgive.

I am not saying what Snape did was acceptable. He needed to find a better way to let his anger out, like talking to Lily, not pushing her away. But what I am saying, is that it is a shame that it ended this way, and with a little effort and empathy, could have been patched up.

Lily had probably been called Mudblood before, but this time it stung. Let us not forget that Snape himself had said that being Muggle born didn't matter. Snape didn't want to be even more humiliated, and made a decision to stop any help. After the indecent, Lily wouldn't accept his apology. I don't blame her, but it's still devastating. The only credit I can give Snape here, is that he was honest. He never once lied to her, and that I honer him for that. He didn't deny that he wanted to be a Death Eater, or the fact that he called every other Muggle born mudblood. He made the last moments of their relationship as giving as he could, being honest, and apologizing.

Snape's life went on, but inside, he was crushed. Lily and James had started going out a year and a half latter, and it was hard to see the girl you love, and have loved for 7 years, go out with the bully you have tolerated since you stepped foot on the Hogwarts express. It is what changed the course of his life.