Do not fall for that trap as it justifies what they want in their head. In fact I would hush about who you go out with and slap a general "friends" on it at all times. She will be happy and civil if she thinks you are dating because like above, she is free from the guilt of being the one who has not honored the relationship as you have done.
Some time back I got a VERY similar exchange, I was a great guy, I deserve to be happy, blah blah blah ... all so she could feel better and focus on OM and that A, I told her that I was a married man and that would be considered adultery, I also went on to let her know what she was doing was disrespectful to me, our M and our family and in no way would I be persuaded to go out (lower myself and standards as she did ... I did not say it that way but it was implied) and do as she was doing just so she could feel better. It was one of those exchanged where I was actually offended that she would assume I was going to just up and go out.
Few months pass and I was having dinner with a group of friends .. 1 guy and 3 gals, she flipped out and was all upset that I have not taken her out on a date in years.
So yeah ... stick to yourself and do your thing, but do not fall for being open and honest, be mysterious and that way she can not justify her OW1, 2 , or 3 ... be the rock and the lighthouse.
