I completely understand your need to move on in your relationship, but i am far from convinced that contact with this woman will give you the peace of mind you are looking for.
It assumes, quite reasonably, that she will even wish to talk to you, and that assuming she does, she will provide a reasoned calm discussion about the situation.
I am sure you have conducted 'conversations' with this woman in your head, but you must know that from sentence one, the 'script' goes out of the window!
You want to feel that this woman bears some of the responsibility for the damage to your relationship - it helps you to avoid aportioning all the responsibility (I am careful not to say 'blame') to your partner.
The truth is, she does not bear the responsibility - he does, and that is what you need address. Your reaction to his behaviour, and whether you can move on with this man and risk further hurt in the future.
You need to look at your relationship with your partner - and not try to analyse his relationship with someone else - that way lies pain and humiliation, or even worse, pity and silence.
Try some Relate counselling with your partner, and see if you can find a way forward together.