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.
Personally I wouldn’t drop a love bomb on anyone out of the blue. But if you’re feeling the urge to reconnect why not try something less intense, like “Hey dreamgirl you just randomly crossed my mind, I used to have such a crush on you back in the day, what’s going on in your world?”