How long do feelings take to fade after a break up?

I read somewhere that it would take around 6 months before you seem to get over love. For some people, they don't ever get over love; they just move on with their lives. But if its infatuation, maybe just a few days. For me, I didn't really get over my previous crush, who broke up with me, till 3 months later, when I first met my current boyfriend.