Disclaimer: I do not own Sherlock Holmes, in any incarnation.
Goodbye Mr Holmes.
Later, Irene wonders why she sent that last text. It hadn't occurred to her to think about it at the time – she had after all had other things on her mind, namely her imminent death.
But afterwards, it puzzles her.
The immediate and obvious answer is sentiment; distasteful, but not impossible. She has already proven she is not immune to it.
Perhaps she had simply wanted someone to know what had happened to her; she hadn't wanted to die anonymously and alone thousands of miles from home with not a single soul to mourn her.
There is also the possibility – probability – that she had wanted Sherlock in particular to know because it was his fault; she had wanted him to know what he had sent her to after giving up the code. She had wanted him to feel guilty. One last revenge; one last move in their subtle, intoxicating dance.
Most likely it was a combination of all these things, and more besides.
It takes a long time before she accepts that there might have been another, unpleasant but inescapable, reason for her actions.
One final truth that she will never fully admit even to herself: It had been an admission of defeat.
She is Irene Adler. She is The Woman. And she has, at last, been beaten.