. . . today, you had the insight to know when enough was enough. I know you are feeling like you let yourself down, but you actually did yourself a great service in leaving that situation when you did. If you hadn't left when you did (and merely powered through the day) not only would you be considerably more grumpy, but the company you were working for would not have been as understanding (or have offered to be reference for you in the future).
Not only did you not let yourself down, but you did something admirable in knowing your boundery and taking care of yourself (in getting out of the situation). Many people would have stayed just to have been eligible for the two weeks of vacation pay, and then left. You showed, as you have in the past, that a person's mental health and integrity are much more important than any amount of money.
Besides, we wouldn't want you to be connected to any of these:
I love you, Sweetie, and I am proud of you!