Detachment is caring about someone while seeing her as separate from you. It is a state of owning your own issues and letting her own hers without feeling responsible for helping her. If you are of the praying persuasion, it's growing out of "Dear God make her come back" into "God, please help us each to walk our own path in wisdom." It is what makes validating possible, because validating is the act of acknowledging her feelings, thoughts, and experience as separate from yours, and of equal validity.
Thought stopping techniques help. When you find yourself dwelling imagine a huge stop sign, for example. If you know a certain kind of day or activity will cause a trigger, plan ahead for it so you don't get stuck in it. Reach out to friends and family and let them know you need them, not to help with W but to help you get out, feel alive, be a part of the world. Make goals for yourself, things you didn't get around to because she wasn't into it for whatever reason. Spend time with your +2. Do things you never imagined you'd do, or that have been on your bucket list. Make a plan for each day, how you're going to be more like your ideal self and less like your every day self. Live as if you are happy until you find yourself actually happy. I know you don't believe it now, but it will happen. The world will look totally different to you when it does.
Me42, H40 D12, S8, S7 A revealed: 7/13 Sep 4/14; Agreed to D 1/15