This negative resignation without notice is intended from a personal assistant or secretary to his or her boss.
{Your address}
{City, State, Zip}
{Date}
{Recipient}
{Address}
{City, State, Zip}
Dear {Name},
I'm sorry to tell you that I will no longer be able to be your personal assistant, and this letter will serve as my official notice of resignation.
I am simply overwhelmed by the amount of work I have to do for one individual, who seemingly cannot take care of {himself/herself} in even the most basic capacity. It's beyond frustrating, and to put it bluntly, I'm better than this.
I'll save us the awkwardness of continuing to work together over a two-week notice period, and just make this effective immediately. Good luck finding someone else willing (and able) to put up with you.
Sincerely,
{Name}