No, don't spill your guts and tell her how you feel. Even though that may seem like what you want to do, if you do this it's a bad move. She'll feel overwhelmed and may see you as weak for emotionally unloading on her. I'd say there's only a small chance it works out with her if you do this,
Women want a guy who is in control, who they feel is calling the shots and who they look up to.
If you tell her how you feel, it's like you are saying ' I want you to decide' when most women want a guy to decide how a relationship goes.
Sure, she will decide if she's interested in you, but it's your job to lead the relationship.
As other posters have stated, do something with her (go on a date) where it is time spent exclusively between the two of you, where you two are alone. See a movie or go to dinner or go for a walk. Go to your place. Be alone with her. Sit on the couch, don't be afraid to have physical contact with her.
If you are alone with her for more than a few hours you should have enough time to make a move (that's plenty) and initiate something. If you spend time alone with her and nothing happens then forget it.
You keep wondering about losing her as a friend. Well, you are attracted to her, you obviously want more than a friendship. You may very well continue to be friends if you have no romantic future together, but you have to be prepared to lose her as a friend as well. You're an adult. Friendships come and go. It's a part of life.