but i don't think, that snape warned d-dore about james and lily, cuz dumbledore said, that snbape wnated to even out that james saved his life, with helping harry on his bewitched broom!
the guilt would have been solved, when snape had told d-dore, that they had to hide...
er,..could sound a bit strange, I'm tired again, like ev'ry day for the last week...
One good act can't redeem any prolonged wickedness. Dumbledore probably still has a use for Snape, otherwise, the only thing to do would be to ditch him when he was no longer useful.
Lily is a mudblood, there is no way Snape would find her attractive. There are probably turn ons and turn offs operating between mudbloods and purebloods.