1. Supporting her daughter means supporting her marriage, not endorsing predators to ATTACK a vulnerable marriage 2. OM is a predator, not a romantic interest 3. Ask for her HELP in PROTECTING your marriage and your wife 4. Tell her HOW she can help 5. Lastly tell her you put a ring on and said forever and you intend to keep that promise until papers aer signed - ask her to HELP you support her going to THERAPY
You will have MUCH more impact if you VISIT her in PERSON and READ the letter to her... sending a letter to her is way too passive...