Nope, I've never shot an animal out of season, BUT I'd never let an animal acting as agressively as you described get with in twenty feet
of me--that's way too close. At twenty feet
, a white tail buck could be all over you before you have time to react.
There was no Monday morning quarterbacking involved (and I wasn't "critiquing" the way you handled the situation).
Since you brought it up, it sounds like you let yourself get in situation for which you weren't prepared. Be prepared, have plan, think about it. (BTW, you wouldn't necessarily have to shoot the deer to change its course, but that is always an option you should be prepared to take. The aftermath of an out of season shooting would be preferable to the aftermath of an animal attack.)