Any response should be short and simple. I have not read this entire thread, however WASs are generally very angry. You may be met with venom regardless of what you do.
I would respond to the "what if something happened?" There is nothing to say. Just a "I will send shorts with x" would be sufficient. I don't think you owe an explanation of why you didn't respond earlier. If I'm reading correctly, she moved out. Decisions have consequences. You can't be at her beck and call. Don't be rude. Just simple responses is the way I would go.
3 kids BD 12/15/13 (IDKIILY. ) Rope dropped Cirque du Soleil style D final 9-9-14 "Some people are born on 3rd base and go through life thinking they hit a triple." Barry Switzer