I understand what you're going through. I fantasize all the time, but it is always about myself being the best at what it is I do.
What kinds of things would you fantasize about if the dreams were about YOU? Can you close your eyes and see yourself doing wonderful things? Not being someone else, but yourself. What amazing things would you do? Steer yourself from being pres or a famous rock star, because chances are you probably won't be those anytime soon (though, maybe?), and concentrate on you being the best you can be.
What kinds of things would you do?
Fantasizing about being someone else is a form of escapism. I choose alcohol and computer games, myself, being somewhat antisocial. These things can be counterproductive.
People who are damaged like us retreat to our womb-state when we feel vulnerable. The guy I just went out on a date with rejected me, and I feel very tender and the need to retreat into a cocoon and drink many bottles of wine and cry. It would be easy to fantasize about my being successful as an actor and composer to cover up the pain of rejection and fear of abandonment I feel now. But...fantasy is just that. If I don't get out there and find someone else to date, I WILL be lonely forever.
So...see if you can change your fantasies to make them about yourself and what it is you can do. And do well. Then concetrate on doing a few of those things.
You will only be a rock star or a president in your own world if you don't do something in the real one. Appreciate the fantasies for what they are....a place to hide, heal and repair. Then come out and join the rest of us in the world!