OH, so Snape's not just a petty asshole, he's also lacking the emotional maturity to get over a childhood crush so instead of moving on and meeting new people he resorts to stalking and sulking in hate for the rest of his life while taking it out on someone who had nothing to do with it and also allowing himself to be manipulated into protecting that same person to the point where he would literally die for them.

I think I'll name my child after him!