What Should I Do About My Older Crush?

Star Girl keeps messing up when she's around her crush, and she needs your advice! —Sparkitors

I'm a girl with a crush. He's smart, and deep, and the bass player of a really awkward band. The guy I have a crush on is my sister's best friend. (We shall call him Sprite, because he loves it!)  We met in our school's law club, and he's really nice. He drove me and a couple friends to a convenience store so we could get snacks before a meeting and we've been awkward friends in the we-talk-sometimes-and smile-at-each-other-in-the-hallway kind of way, ever since. There have been some, um, complications though...

1. His sister, who is in my grade, hate's my guts (and my sister's too), for absolutely no reason at all.

2. My friends were OBSESSED with him and kind of asked him to his prom, and creeped, and called him on his home number, and wrote poetry to him. They started calling him Sprite as a pet name. It was pathetic.

3. We were joking about prom, and Sprite asked me as a part of the joke. I replied in a mean way. This has happened a couple times, actually.

4. He's my sister's best friend and likes someone else (who is my sister’s other best friend).

5. During a "mock trial" he was my witness and I did awfully, I asked all the wrong questions, pronounced things wrong, etc.

6. We (as in he, my sister, her other best friend, and me) walk together to the parking lot after school, and when he parks far away, we drive him there. It's an all-around awkward thing.

7. Oh. I almost forgot... he asked to sign my yearbook and wrote "Hey, how's it hangin'? -Sprite (except he wrote his real name) “P.S. If you need a prom date in two years, I'm available.” My sister asked him about it and he said he was serious, saying he'd drive down for the event, followed by, "She so wants me." Later, he asked for an answer... I panicked and said "neither of our sister's would approve." And then I walked away...

I'm so screwed. I always get all panicky and say something stupid. It’s getting to a point where I try to talk myself out of this craziness, but then the next time I see him, he does something hilariously adorable.  ... Sparklers, Manklers, any help?

Advice for Star Girl, in the comments!

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