If she is still with OM, all of this is just a temp check.

She's feeling anxious about losing you and wants you to reassure her you are still there so she can go back to dating OM.

I think I would just say "If you are still with OM, there is simply nothing to talk about".

Blows my mind that she can cheat on you and move in with OM and still say ILY, IMY. How incredibly selfish, I hope you can see that.