Although it may sound cliche, life truly is a roller coaster.
Your going to have your ups and downs and there will be times when people, even your own family, don't love, let alone like, you.
Advice? Don't give up. Yes, it sounds cliche, but growing up and showing those that doubted you from the start is one way to say that you don't give a crap what others think.
Show them that you are important. What your father said was truly wrong to begin with.
What he meant to say was, "One day, you'll find someone and you'll turn their frown upside down." smile