I just did a little catching up on your sitch. Brook is right on with this. They create their own reality to justify their actions.
I'm sorry you are finding this info out. It's the PITS! I didn't know for months. It caught me way off guard, as I really believed him and he hid it until he couldn't anymore.
I went through various things about what I did want to know. My sitch is a little different, but the hurt of ow is the same, I'm sure.
For awhile (it's been a month since I found out) I didn't focus on her (by "awhile", I mean a couple days). Then I wondered the same as you... about closure and everything. So for a couple of weeks I didn't really find much out and kept "her" at an arms length, yet it always festered at the forefront of my mind. It was a back and forth battle for me. But, I will tell you what... I have learned SOME things about their sitch. I don't want to know too much, it is just hurtful, and I don't want my mind to really focus on it. For example, I just found out they (along with her 2 yr old) went on a cruise in May (he said he was away for work). If I let it, this really gets to me. I think about them traveling together, him taking care of this little kid, the 3 of them sharing a room together. We have been together since teens, so really, we've experienced everything together. We've never been on a cruise, so this bothers me. See... it can take control of your thoughts... you have to stomp them out!
On the other hand, some of the stuff I have found out has helped me. Nothing in particular, I guess, has just answered some questions. That keeps my mind from spinning.
So I guess it really does depend on you and what you do want to know. The bottom line is this, putting some of the puzzle pieces together has helped me move on. I keep in mind that their r is based on lies, secrets, and infidelity. They may think that they are living the dream, but they are very selfish people. Anyone who does that is selfish. She put herself before my kids and my family. He did the same. I don't see them putting each other before their own needs for a long time. There is way too much interference, and they only care about making themselves feel good.
If you do find out info, make sure you do it from a very detached place. Make sure you can bear it. You don't need to know every little detail. That is like terrorism to your brain and heart! If you need answers in order to put your mind at rest, so be it. This may not be what others advise you to do. I am just giving you my perspective. This is new for me, but I am making strides.
I wish you the best of luck. I know it's tough, but it seems like you are doing very well considering the circumstances. I will be cheering for you!