If you want to work on this marriage, fine, if you don't, I have some decisions to make in the next few weeks.
Or how about:
“Wife, it’s abundantly clear I am the only one invested in saving this marriage. You have made your intentions to break our family apart and pursue OM (insert actual name) clear. I deserve so much better than to be a third wheel in your affair - so I happily accept your choice and wish you both well 👍
Today I filed for divorce. My lawyer is xxxx *insert name/address* and they will contact you shortly. Hopefully we can amicably agree to financial and custodial arrangements without expensive legal representation, but initially while the dust settles, please direct all enquiries to my lawyer.
