What happens when Juli sees Bryce with Shelly Stalls in the novel, Flipped?

When Juli sees her mortal enemy, the delicate Shelly Stalls, holding hands with Bryce, Juli sees red. Juli senses that Bryce does not really want to be with Shelly. He'd rather be with her but Shelly is aggressive and Bryce is too polite to protest. Once again, she figures she needs to rescue him and that is how the fight started between her and Shelly.