I also guarantee that she will have a place of her own even though her mother has offered for her to move in with her to break her contact with the OM. Having a place of her own will allow her to continue seeing the OM.

And that "open apartment" she mentioned, she may not live there but the two of them will be using that apartment for other specific purposes. Good planning on his part that he already has a "lair" specifically suited for this purpose, open, no occupants, other end of the city, far away from prying eyes, discreet - perfectly suited for this purpose.

She brought up the separation as well, again.
She's been thinking about it more & more.
Those acts of affection: kissing & hugging, she probably does that more now than she ever did in the past, she feels guilty for what she's doing to you and is over-compensating with affection towards you to make you feel better.

Those kisses I'm sure taste bittersweet when you know she spends time with the OM.

My descriptions are graphic and are done so on purpose.
Time to open the eyes a bit Tristan.

And please stop allowing her to use her sexual abuse issue as a crutch for her actions... "this happened to me so I'm going to do this and blame it on these past events and how they traumatized me". Someone posted earlier, she's an adult, allow her to claim responsibility for her actions & decisions and allow her to know the consequences of said actions.

When you finally do ask her to choose between you and the other man and she can't make a decision, throw this monkey wrench into the loop... "I guess it's ok for me to start dating and meeting OTHER WOMEN and maybe I'll find out first hand why it's such a hard decision for you to make."

When confronted with that possibility, her attitude may change, if it doesn't, it's just made your decision even easier.