Hi Gut, Sorry to see you here, none of us want to be here. but, it is a supportive place and literally saved me emotionally during my sitch (still is).
I think it is a personal choice for you whether to confront before Christmas or not. I think that i, for one would wait. But, only you can know what you can tolerate or not.
You will have to have the conversation though.
When you do, plan it in advance in terms of what to say.
When I confronted my H, I had been on this forum long enough to know that I needed to do it calmly, with assertive boundaries, but also letting my H know that I would fight for this M.
I said something like this: "I know the truth now about you and OW. I want you to know that I am devestated, but that I also love you and I am going to fight for this M. I am willing to forgive you and work through a healing and re-building process, but only if OW is out of your life completely in every way." I was very calm. I was very firm. I was very sure.
My H was very surprised by my reaction, and, as a result, there was no fighting, yelling, drama etc.
After that, I DB'ed my butt off. I remained firm in my position, I GAL'ed, I did 180's, I didn't pressure, I made myself "the better option". OW took me finding out as an opportunity to pressure H to leave me and kids immediately and move in with her. H was now very confused and torn. He waffled for 3 weeks, then ended the A and re-committed to our M. We are now slowly, painfully at times, piecing our M back together and making progress.
I am not saying that is how things could turn out for you... they could, but no guarantees. But, what I am saying is that you need to apply the DB principles both in how you confront, and how you handle things before/after the confrontation.
I am still pretty new at all this myself, so I am sure some of the vets will be along to help....
In the meantime, know you are not alone and the good people here understand and are with you...