My situation is differerent from yours. They live in another state. Also, I warned her I was going to tell her husband about it so I imagine she described me as some jealious crazy person.
I'm glad I did it, but my husband and OW were FURIOUS!!! My husband called me extremely angry and gave OW my home phone number. She called and explained that she was happy in her marriage, didn't plan to ever see my husband again and said her husband was very angry about me calling him (saying I was harrassing them... I think this was a bluff on her part because she was so upset about me contacting him. He was very nice on the phone so I think she just basically was trying to scare me so I'd stay out of her life).
In your situation, doing this anonimously sounds like a good idea. Still, they may suspect you did it and be very angry. If there's anyway you could get a male to call and leave a message or tell him (or have someone else write a letter in their handwriting), that would probably be best. Good luck!
There is no arriving, ever. It is all a continual becoming.