You wake up, in the middle of the night, still soaking wet from the sweat you and Ellie worked up. Seeing she is still asleep, you carefully put your pillow over her face, and smother her!

Whe she stops struggling, you remove the bracelets from her right wrist. You then use the bracelets to make the other cheerleaders forget all about theirs. After which, you restore all of Ellie's victims to normal, and similarly give them amnesia as to what happened. Maria, in particuliar.

Then, you shrink Ellie's body, and flush it down the toilet. Poetic justice, for such a piece of crap!