Stay strong, focus on you, and prepare for her to reach out. I guarantee that she will. Nine months after the ultimatum, my WW still reaches out on occasion and complains that I never respond to texts or calls. And no matter what you say or do, you will be Plan B for a long time. You need to work on you so that you are strong and able to resist the temptation when it comes.
And to answer your future questions, I vote for complete and utter radio silence in response to whatever she says or writes.
