Here is a part of Dev's letter that addresses the A head-on. We've also helped HP compose his no A letter to his wife too.
I want to be clear on some things. One is that I do not want a divorce, but will not stand in your way should you choose to continue on this path. Two, I am not willing live in an open marriage with a third party.
We will not be friends should you decide to proceed with a D. Make no mistake -- if you choose to end our marriage this way, by continuing your affair with OM. It is incredibly disrespectful to me, to our marriage and our family. We will co-parent our children, and I will of course be civil and courteous, but this isn't how 'friends' treat each other.
Going forward starting now, as long as you are involved in an affair with the OM, our communication only be focused on the logistics of the children's schedules, their issues, and exchanges.
We have some decisions to make here. When you’re ready, please let me know your thoughts.