My method is try and get feelings for someone else until the hurt and feelings of being rejected go away.
I got rejected by a guy I liked for 8 months as he liked someone else. I cried for a few days, went out drinking with friends and kissed a few lads.
It helps knowing that there are other fish in the sea who actually find me attractive etc...
PS. I know this question isn't based on a break up or divorce, but it fits into the category.