“I know that your relationship with OM is more than friends. This is disrespectful to me, the kids and yourself. For me It is unacceptable behavior that a married woman acts in these ways. I will not allow my children to be part of this situation either. I know I cannot stop or control your behaviors, nor do I want to, but This relationship is not working for me and I am moving forward without you. If you decide that you want to work on this marriage and this family you can let me know and we will see if that option is still available. I will also have zero tolerance for this guy or any guy to be in or around our marital home and to have any contact with our minor children. I pray that you find what you are looking for.” Then just walk away.
This is the second time you have proposed an ultimatum message. I’ll say it again, it’s not going to work. Every time you send an emotional or blackmailing type message (if you do X then I’ll do Y) your marriage is less likely to be saved.
I really think you need to go back to DB basic principles..
Rather than write some long winded, manipulative message, and given you are telling her above that this relationship is not working for you, perhaps try sending her this instead:
“I don’t want to be in this relationship any more and will be ending this marriage.”