I agree with LH. Don't say that unless you are willing to follow through. Based on her "current feelings" she is likely to be fine with it but as we all say, feelings can change.

I think it's ok to tell her you know about the OM and you can state your boundaries. "I know you are seeing OM and I think it's best if you find another place to live"...or something to that effect.

As long as she's with OM you separate yourself (without moving out) from her.

H 37
W 31
S 2

T: 7
M: 4

BD 12/18
Separated 2/19
Living back together 04/06/2019
W Moved out again 07/15/2019