Vili Fualaau Out with 18-Year-Old Daughter After Separation from Mary Kay Letourneau

Vili Fualaau was out with his daughter in the wake of his separation from Mary Kay Letourneau ... but let's get real -- holy crap, she's 18!

Vili and Georgia hit up a Quick Mart in Seattle Wednesday -- she's the daughter to whom Mary Kay gave birth while serving a 7-year prison sentence for having sex with a then underage Vili.

We broke the story ... Vili filed for separation from Mary Kay last month after 12 years of marriage. Mary Kay's contesting the separation for some strange reason and wants Vili's petition dismissed.