At times I feel like I am pi$$ing in the wind and this is all for naught.
Yes. Maybe it is. Maybe not, but maybe yes. Getting attached to the outcome is not what you want. The idea of DBing is to improve yourself for you, not for your spouse. You're not detaching at all and you're still trying to control her emotions.
Even if she comes back to you (which at the moment it looks there's a long way to that) your control issues will drive her away again. This is where you need to work on yourself. Not trying to analyze the situation over and over again, trying to justify yourself. She internalized hurt because you were so controlling that she was afraid to show it. So stop trying to get a reaction you want out of her and let her live her life. You don't have control over whether she comes back to you or not. You can only better yourself in hopes that she will and you're not doing it.
Accept that there is only one thing you can change in life and that is you
