Puppy, I would love to talk to him and really do want to issue ultimatum, because as long as he is involved in A, there is no moving forward for us and I am sick of being in limbo. Would like to tell him either quit his A and work on our M, or else move out (would not say "divorce"). I would say this, except I really do not want him to move out! How can I confront without issuing ultimatums?
You make it about YOU -- a "boundary", not an "ultimatum."
Example:
ULTIMATUM: "You need to stop seeing this other woman, or else!"
BOUNDARY: "I am not willing to live in an open marriage."
ULTIMATUM: "You have to stop text messaging her from inside our home!"
BOUNDARY: "I cannot live in a marriage where my husband disrespects me by text messaging another woman in front of me. It violates my personal integrity."
The key to effective boundary-setting is that you basically say "Look, you're an adult, and I can't tell you what to do. But I absolutely CAN tell you the kind of marriage that I'M willing to live with, and these are deal-breakers for me. You can do whatever it is you wish, but know that my response will be based on what you decide, and I won't wait forever."