Here are a few cleaner, more natural rewrites:
Polished storytelling:
The afternoon before my sister’s wedding, she looked at me in the mirror and said the perfect gift would be my absence. I didn’t cry… I just walked away.
More dramatic but smooth:
The day before my sister’s wedding, she told me the best gift I could give her was not showing up. I didn’t react—I just went quiet.
Short viral hook:
The day before my sister’s wedding, she said the “perfect gift” was my absence.
If you want, I can also turn it into a full story post or help you make it more emotional or click-friendly without sounding fake.