Lisa, if Mrs. Pilot is entitled to spousal support under the law then it doesn't matter WHAT she spends it on -- she's entitled to the support even if she does spend it on a waxing appointment or a bar tab or whatever.
What I read in his post was him just cutting her off. If he yanks the rug out from under her the way I read it, then she will turn to the law. Guaranteed. I don't know if she's actually entitled to anything given the term of their marriage and that I don't know what she does for work, and possibly she's entitled to at least some amount of child support.
Given that he's feeling unhappy with the way finances are being dealt with between them (as I think is reasonable under the circumstances), it would be better for both of them and for his DBing if he regularized exactly what amounts he gives her. Her treating him like a piggy bank isn't good for her respect for him, and isn't good for his goodwill towards her either. Lose-lose.
Once you've got a regular system in place then SOP should be NO EXTRAS, NO EXCEPTIONS.
Me42, H40 D12, S8, S7 A revealed: 7/13 Sep 4/14; Agreed to D 1/15