This is certainly not an easy situation. There is no one right and no one wrong way to go here. But the more you think about how your W views the things you do, the unhappier you will be. Remember, she is the one leaving, so she is painting everything you do the blackest of the black. If you give her money, you are controlling because you want to keep track what she spends it on. If you cut her off, you are controlling because you want her to be dependent on you.
The difference between the two choices is that the latter helps you detach. It is momentary. You cut her off and it is done, she can complain about it for the rest of her life, but she will simply be repeating herself over and over again.
The former choice, budgeting with her, leaves you in a continuous state of conflict. IMO it is lose-lose situation.
