I think Snape's reaction was quite good. His level of rage was perfect, he seemed really really mad. If people don't think he was mad enough, they should also remember Snape had just been tortured after all....Plus I doubt that Snape has forgotten his guilt over what he did to Lily. I like that Snape didn't completely cut of Dumbledore (although he's implied that he would if Dumbledore tells Harry...). Oh and I noticed that you explained about Lily's memories being copies and stored in the pensive.
Author's Response: Oh thank you :)
I liked Snape's reaction too. Obviously, or else I wouldn't have posted it... but yes, I'm glad you agree. He's not angry enough to completely cut off Dumbledore... but he's angry enough to threaten it, and he is angry enough to get worked up into a rage.