Thank you all for the comments. It's encouraging to read so many of you saying that these are signs that things are moving in the right direction. I need that reassurance sometimes because I can only see the sht coming at me from where I stand.
Yes, it was my W's sister who wrote the email but it has my W's words and justifications all over it. "You pushed my sister into doing this", "You're involving us just to humiliate her", "You should have talked to her first before involving anyone from the family" etc.
I replied with Puppy's text and one more line about the "talking to her" part. I said I tried really hard to talk to her and suggested going to therapy, etc (1 month ago) but she wouldn't agree. Instead she got involved with someone else. I went to our place on Saturday and she wasn't there. What else am I supposed to do?
Finally, I said that if my W wanted to say anything, she can contact me directly and stop sending messages through her. I won't read/reply to any of her emails anymore.
Separated: March 1 * Affair discovered: 20-March * Exposed: 27 March * Def. separation: May 1st *