When I'm Wrong, I'll "Definately" Admit it

I’m pretty confident in my English skills and spelling ability. I know how to form a sentence. I have all of the appropriate books on my bookshelf to help me out, should I ever get in a spelling or grammar bind.

Then last night, as I was instant messaging a friend, she corrected me on a word I typed. It went something like this:

NE’smom: We need to do that
Green3: Definately
NE’smom: it’s definitely
Green3: no it’s not
NE’smom: No, I’m right. It’s definitely. I, not A.
NE’smom: Look it up online so that we know what is correct
(me, frantically searching dictionary.com)
Green3: GOOD LORD! I AM WRONG!
NE’smom: I’ve noticed that you’ve always spelled it wrong, but never said anything

And then I continued with much moaning and groaning about having to retrain my brain to spell it as “definitely” after 35 years of spelling it as “definately”. I am definitely ticked off.