This quote capsulizes the profound human experience of regret and the longing to reverse past actions with the benefit of hindsight. Tony’s admission, brimming with remorse, highlights a pivotal moment where a seemingly ordinary decision—a choice to attend a party—cascaded into life-altering consequences. The phrase "I was an idiot" accentuates the rawness of self-judgment and accountability. It’s an honest confrontation with one’s mistakes, exposing vulnerability that many can resonate with deeply.

Regret is a universal emotion, one that underscores the imperfect nature of decision-making under uncertainty. Tony's reflection painfully underscores how an impulsive or misguided moment can unravel what we hold most dear—the "love of my life." This narrative moment serves as a warning about how critical our choices are and how often they are intertwined with chance, timing, and external factors beyond our control.

Moreover, the quote speaks to the torment of living with "what ifs." Tony’s wish to "undo everything" suggests a desire not only to change a single event but to erase the ripple effects that damaged his future happiness and relationships. It's a testament to the fascination many people have with time travel or second chances—even if these remain impossible.

The presence of Kelly in the sentence personalizes the regret and sorrow, potentially the listener or the one close to Tony, which implies a relational dimension to his remorse. It reflects how our actions impact not just ourselves but also those around us who share or witness our journey.

Ultimately, this quote from "Undercover Desire" evokes a mix of melancholy and caution. It invites readers to reflect on their choices and relationships, and how sometimes, our greatest lessons come burned into our memories by regret. It's a raw, emotional reminder to tread carefully in moments that feel trivial but may hold the power to shape our destinies in profound ways.