Should I tell her I know?

[Puppy Dog Tails]

My suggestion was, you move back into YOUR home, as YOU did nothing wrong. If she chooses to leave, that's her choice -- you are not "kicking her out."

I personally doubt she'll leave.

As for this:

I asked her tonight. she said its not because there's someone else involved.

that's just a bunch of affair script b.s.

Puppy