I also find that her last text to him after he said he was boarding to go home said "no, want you back "!!!
What, you've never said goodbye to a good friend and express the desire that they could stay? Again, this could be a totally innocent expression. (I'm not saying it couldn't be something else entirely, but you have no real evidence that it is something else.)
Just bewildering why she would send over 130 texts in 4 days after meeting but only a handful before?
Out of sight, out of mind. When he showed up for the reunion, they started chatting again. So lots of texts. This is human nature. If my wife had an ex boyfriend show up to visit in our city for a week and they met up, I would expect they might well text often while he was in town. It would not bother me in the least. But then, I trust my wife explicitly. Just as she trusts me. Seems to me the two of you have trust issues if you get all bent out of shape over some texts which you don't even know the content of.
why she would send him a text saying I've been unfaithful which incidentally I haven't
Only she can answer this one. But we humans say stupid things sometimes when we want someone to show sympathy/compassion for us. Maybe she thought he would be more attentive toward her if he felt sorry for her. Maybe she was looking to see if he was willing to have a brief fling with her. Maybe you two need to sit down and have a serious discussion to find out why she would say that.
Maybe she feels something is missing in your relationship and she is starting to look for that outside the marriage. (I'm not saying she is right to do so, just that maybe she is.) You certainly have a trust issue with her. The sooner the two of you sit down and talk about it freely and without being accusatory, the better for the long term relationship.