Found this gem from Ready2Change in the boundaries thread...I've changed OW to OM to fit my situation:

Start Boundaries with I statements, not YOU statements:
"I will not live in an open relationship"

"I will not tolerate you contacting OM in my presence or in our home"

I will not tolerate you spending our family finances on having an affair"

I will not tolerate you contacting OM"

Follow those statements with this thought process:
If you continue this disrespectful behavior, I will take this action.

" I will not tolerate you contacting OM, If you continue contacting the OM, I WILL file for D."

M-43
FWW-42
T 20
M 16
DD10
DD8
EA: 1/10
Informal separation: 6/11/2010
Headed for D: 7/6/2010
Piecing? 9/10/10