Feelings I had for my classmate were obviously one-sided (pretty sure of it), so I made a reasonable decision to never confess to not make things awkward. In a few years since we graduated I finally moved on, although I never loved anyone this much since.
Yet all this time I had a desire to tell her about them. I would definitely want to know if someone loved me this much ever. Would she? I don’t know. I don’t even know if she is in a relationship right now or not.
I would really want to cite some scientific study that “Over 80% of girls have their self-confidence lifted after being told they were secretly admired (p<0.05)”, but can’t find one.
You don’t love her. You barely know her. It’s been years, you have no idea what she thinks, what she’s done, what she would do, etc.
What you love is some ideas you have about her.
You never dated her. You never saw what she was like outside of class, at home, at work, with her friends. You don’t know if she’s honest, or cruel. You don’t know what her political beliefs are, or her religion. Would she kick a puppy? Is she an addict? Is she selfish or generous? Is she clean or slovenly? Does she have a partner? Does she have kids? Is she even hetero?
This is all aside from the fact that you’re imagining a connection that you know isn’t there. Telling her has nothing to do with her and everything to do with your own ego.
This way of thinking with the fantasy of loving someone you don’t really know and the idea that your feelings years later are important enough to barge into her life with a confession of love without even finding out who she actually is and what her circumstances are… This is a red flag that even in the incredibly unlikely event that she’s single and into you, you are not going to be good for her.