OM is nothing more than a friend who happens to be male. If there was ever more than that, it's gone.
So why is he so important to her?
Because she doesn't see anything wrong with having male friends. From her perspective, you're being unreasonably jealous.
IMHO, it is your business. Her contact with him hurts you. But, from your W's perspective, it's none of your business - or at least shouldn't be.
That's why she thanked you for butting out. She didn't expect you to, but thinks that over time, you'll truly shed your concern.
The reason your W doesn't see that this isn't "helping your progress" is because she thinks that in time, you'll get over it. For this reason, she thinks it is helping your progress. She thinks it's helping you to progress to a place of trust the longer she sees him without doing anything wrong.
