ZenMe,
Something that worked really well for me is mindfulness. Google it and you will find tons of information.
The I used it was whenever I caught myself focusing on her, arguments in my head, missing her and anger for example I would ask myself a question to bring myself back to the present moment. Questions like who are you talking to, and that isn't real.
Just something to slow down the crazy train in my head and give me a chance to jump off. I don't use the questions any more but I still use mindfulness to help keep me centered and in the present moment.
Your friend,