So my brother is engaged to a pretty nutty chick. She is very jealous, reads his emails and texts, and accuses him of stuff all the time. A couple of months ago my brother called me, my mom, and my dad one day, and with her in the background yelling, "admitted" to each of us that he had cheated on her and that the wedding was off. The wedding is planned for summer of 2018, so I don't even know what that means, but whatever.
FWIW, the "cheating" was my brother receiving a topless pic, and going to get a happy hour drink with, a co-worker, 18 months ago. This was before he was engaged or living with the fiancee, but after they had been going out for a while. At any rate, nothing physical, and after the happy hour he sorta wised up and stopped communicating with the co-worker. She discovered this by reading his old work emails.
My brother has been in full-blown "I can't lose her" mode since. Anyway, today I get an email from his work account that starts off "Hey [my full first name]". The email asks me to write up a deed to put fiancee on title to his condo (I'm a real estate lawyer). It didn't read like his writing, and to confirm my suspicion, I flipped through the last 50 or so emails from him to me, and none have a salutation of any kind. Plus he's never called me my full first name in his life.
I have no idea how to respond. If I call her out I fear that it will be the beginning of a wedge bxt us, and the first step towards estrangement (isn't this how it starts?). Any bright ideas?