I love someone who doesn't feel the same way

We clicked too. Were best friends up until recently. However that doesn't mean that you'll click in a romantic sense. Maybe she only ever wanted a friendship.

I was dead certain that she fancied me for a long time. I thought she was always flirting with me. Turns out she had no such feelings and was just being friendly. Sometimes our feelings cloud our judgement.

I think I need to do a lot of thinking, I'm crazy about her but she's breaking my heart too.

Maybe your problem is you are doing too much thinking and making it a drama.

Let her know part of how you feel and then she either feels the same way back and wants to engage or she does not. If she doesnt, then move on.