Exactly. Quit stalling and just tell her already.
If you truly feel like you've already lost her, might as well let it out - because IF she does reject you, it wouldn't change [much] anyway, seeing as how you've lost touch with her at this point. The more you delay, the heavier the burden this is. You're far better off confessing than living the rest of your life in regret, wondering how things could've turned out had you taken action NOW (or even earlier).
I was in a very similar situation with a girl during my junior and senior year in high school, and took advantage of graduation night to give her a letter confessing my feelings; even though we've gradually drifted apart throughout the last few months of 12th grade. She messaged me saying that she'd still like to continue our friendship, but we haven't even spoken since (this was June of '06). Obviously she doesn't care, and I've moved on from there. The problem was HER, her insecurities and fears of the social stigmas, and inability to cope with the situation. I've gotten over it since then....and this was a girl I valued almost more than life itself and always put first on my list. I was extremely head-over-heels for her.
Simply put, if it doesn't work out between you two, you'll get over it over time and learn from it.