Kinda hard to tell from the context, but I know that in some places (my home state, for example), evidence of an affair *after* you separate (but before the divorce is final) can be used to show that you were cheating when you were still together. which, you know, can definitely toss a bit of alimony into the mix. (or could have been the reason for the separation to begin with)

also, the note she wrote to him on the receipt (kind of confused by that, but whatever) said something about him still having the girl's number in his phone. and yeah, I can see not having a leg to stand on if she's bitching about who he messed around with after they split - but if they're trying to reconcile, and he's still involved with the chick? totally not cool.