silentscream13 -
I'm right there with you. You have FB messages, where as I have phone records and GPS records. I'll be sitting around and think: What was she doing when I called on so and so date? Or, what did she do after she posted that photo on FB? Stuff like that all the time.
So, I'll look at the phone records to see when I called (or when she posted on FB), and then I'll compare that to the GPS records. It tortures me because I still keep finding things.
One thing I am going to do for myself, is to sit down and create a timeline using the records I've got (including both our FB timelines). I think it will help show me the full extents of the A and provide some closure (she is unremorseful and still denies most things). Everything will also be there in one place. Sometimes when I post on SI, I'll read what I wrote and think "who in their right mind would stay married to such a hurtful person". So, it helps me to see it in black and white. (I should probably start a journal.) It relieves my own guilt for wanting a D when I really and truly do not believe in D.
A few things in your post stood out to me.
He told me he has no emotional tie to her. It was just someone to make him feel better about himself.
Feeling good about yourself is all about your emotions. So, if she was doing that for him, it was emotional.
He asked if I wanted his truth or the truth that I believe.
I've heard the same line from my WW. I've caught her in more lies than I can remember at this point. In my case, the truth I believe is based on the evidence I have in front of my own two eyes. I don't believe a word out of her mouth, and I question if she even knows the truth at this point after all the lies she's told. Once you tell a lie so many times, you start to believe it.
Someone else suggested a polygraph. I second that. IMO, his willingness to do it or not speaks volumes. I asked my WW to take one, and she flat out refused immediately. I told her that's all I needed to know.
Finally, it sounds to me that he's trying to minimize what he did so that HE feels better when it goes away. If he cares for you the way he should, he'll answer you questions, deal with your hurt, and put you first for as long as it takes.
I know that at some point, I have to stop trying to piece the past year back together so that it makes sense and move on with my life. I'll do that when I'm ready. I'm only 4.5 months from my first DD, and almost 2 from finding out about her rendezvouses at his house/rental/houseboat. Things are finally starting to "stop spinning". I've got my feet back under me and can think clearly most of the time.
So, you need to stop torturing yourself by reading the FB messages. But, stop when you're satisfied and have done what you need to heal. There's obviously things you feel you don't know (I get it, because I'm there too). You'll get to a point where you're like "that's enough". I'm getting there. I don't obsess over my "evidence" nearly as much as I did when I first found out. You'll stop too eventually. Hang in there, and stop punching fence posts! Hit him instead! He can take it!