<human>: Can you summarize the given text in a few sentences?

For the last year I've gotten close with my friend from high school and her sisters (early-mid 20s). They helped when one of my parents passed away, as they've been through the same thing.

Full Disclosure: For several reasons they're the only people I hang out with (another issue entirely). Her sisters usually have 1-5 friends over when I'm there, whether that counts/matters or nt. I live 45 minutes from where I grew up and only have one friend who lives close.

We hung out the other night and when I got there another guy was there. She broke up with her long-term boyfriend last year and hasn't dated anyone since (that I know of). Seeing that broke my heart. Clinically I've known all along that it was bound to happen, but there's nothing quite like seeing it first-hand. Part of the problem is that I'm not sure what her relationship is with this guy, but they were flirting pretty hard.

Turns out I have feelings for her. I know that hanging out with only her is the biggest factor at play here. Based on things she's said, I'm 97% sure she's not interested in me, and that 3% is only there to keep things interesting.

How do I tell her I need to keep my distance without sounding foolish (or your best adjective)? I get along very well with her sisters, should I talk it out with one of them first?

Thanks in advance, I know it's disjointed and not the most complete picture but any advice will help.
<bot>: Have feelings for my friend but I'm positive she doesn't for me. How do I tell her I need to keep my distance without sounding like an idiot? Should I get advice from her sisters that I'm also close with?