A bit of advice on setting the following boundary?

Considering telling W she needs to leave, now, and that I will care for our son until her first scheduled week with him. I cannot allow her to continue to use our home as home-base for her affair, and I also cannot allow our son to have contact with OM. Additionally, that while my son will be with my parents for the move-out, I will be present because I want to know who is being let into my home.

Given the situation as I have laid it out, would it be wise to do this, or should I leave it be? She will only be in the home for another week.

Should I approach it in exactly this manner, or should I use a little more finesse?

Me: 30, W: 29
S: 4
T: 14
M: 5
BD: March, 2015, ILYBNILWY, IDLY, Need Space
OM, EA/PA Discovered (drunken kissing, she says she stopped there? NOPE!): March 2015
S: April 25th, 2015