Why do I rely on men for my self worth?

I have a bunch of great friends, male and female, but when I'm feeling really horrible about myself, I often turn to an ex-boyfriend or an old friend w/ benefits to either emotionally compliment me or physically please me... Right now I don't have a boyfriend, a friend with benefits, or even a man who is interested in me... I feel absolutely worthless and though other people tell me I am worth something, it's not as fulfilling to hear that from a particular ex of mine, or a particular FWB I recently ended things with.... why do I do this?? (BTW I'm an only child, my Dad left my Mom when I was 16 for another woman he had worked with for 11 years previously... they remarried when I was 19-- I'm now 24. He lives a planes ride away and is there for me but listens to and goes through his wife for final decisions on everything and opinions on everything...)