This is brilliant! You managed to give Snape his life after death at the expense of Ginny Weasley. At first, I actually wanted him to admit what had happened, but as the story went on, I was glad for his silence. Severus is a smart man (woman, now?), and after years of being her teacher, he will have figured out enough of her mannerisms to get by. Also, any changes in her behavior will surely be chalked up to the battle and everything that happened.
Now that I think about it, even if Snape had tried to tell them what happened, they wouldn't have believed him, and it might have earned him a trip to St. Mungo's for his trouble. Wonderfully executed and in such few words. Bravo!