Grow up ...that's what you do. I don't mean that if you aren't a child that means that you'd never have feelings for someone you know you shouldn't gave feelings for. If however you aren't a child you know that you deserve a guy that is the best for you. So you move on. Sure you might not feel great for a little while. That the thing about being grown up also. You know that you will sometimes not feel happy but you also know this won't last forever.
