“I used to have a big crush on you” totally legit, playful, good way to see if she was ever into you.

“I used to love you” that’s weird. If you’re still friends don’t you still love her at least platonicly? The explanations you’ve been giving in this thread can only make the situation more strange and more awkward. Love means a lot of things to a lot of people so it’s a weird word to use in the past tense about a friend you used to also be attracted to.