MasterChowmein said:
I can kinda see where you're coming from. I do have the odd friend who knows me well enough to read my sarcasm via text. However, even if you believe this to be true, it's risky to assume that somebody can tell that you're sarcastic online. Even with my friends who know my sarcasm, some things can still get lost in translation, so I couple sarcasm with a

or

or "jk!"
Think for a second, though. You figure that she just knows that you're sarcastic, but this isn't infallible, no matter how well you think she knows you. All it takes is the slightest off-mood and if you gave no further indication that you were sarcastic, think of how you just came across. People get busy all the time when chatting online; the difference between online chatting and talking on the phone is that you can take your time, stop and go as you please, etc. She might have been distracted away by some situation that made her less susceptible to your sarcasm. Then, if she doesn't realize you're sarcastic, then how do you think you came across by writing "So you ARE ignoring me. Well that's just rude"? Then, as a courtesy, she responds, to let you know that she's there, or she's back, or something, and rather than carry on a conversation, you reply "You wouldn't have even replied if i didn't call you on the fact that your ignoring me."
If she was in the middle of a situation that was somewhat less than pleasant, it's not hard to see why she might have identified the conversation as being something she didn't want to take part in, and called it a night for you. I can't tell you if she was phased by it or not, but at any rate, what you did was not very well played, based on the information I could gather from your post.