I guess it is possible to "not" focus or "stop" thinking about someone. But you got that don't think of blue problem.
Some people handle relationship loss by going directly into another one. Other people decide to stay away from new relationships at all costs and find out who they are by themselves, outside of the previous relationship ... especially if that relationship lasted a long time or they changed a lot during it.
Other people decide to start taking time out for themselves and being really "selfish." That is, engaging in a lot of activities that they really, really like. A female friend of mine chose this, and it really seemed to work for her.
My way of handling a really difficult break up was to focus on the negative qualities of the person and making a lot of jokes about the situation.
If it's any consolation, these massive changes this woman is making should indicate the profound effect you have had on her. She seems to have had to go to extremes to deal with the situation herself.
If it is right for you, find new venues online and elsewhere to hang out. Places you like that she isn't. Cut off contact with her.
Sometimes you also might want to feel the hell out of the feelings you're feeling instead of avoiding them. Wring them out, so to speak.
Sometimes, I just want to watch or listen to something really, really sad and give a good, solid cry. Afterward, I feel cleansed.
Some people even go on vacation or visit someone somewhere far away so that the associations with the person just aren't there. A friend of mine had his father die, but then (I forget why) had to go to Europe. There was a lot going on there, and he was needed for several projects. He was so involved and so far away from his family and things to remind him of his father that he said the grief was actually minimal.
Later on, it might have been a year later, he started grieving, but he said it wasn't overwhelming. I found this series of events strange, but they made sense to me. Dunno if I'd do the same. I guess it depends on the intensity.
There are lots and lots of different ways to handle loss. There are even NLP patterns for it. I believe you can find some in Heart of the Mind.
Believe it or not, Anxiety Free might help. Also, New History Generator. Prosperity is also another one. Anxiety free has a pattern in it that'll probably help. Basically, you bring yourself into the future when you have overcome the loss and gotten yourself back on track, back to your normal sense of self and being, and then look back at all the changes you had made now that things are better. What a relief.
I am sure you'll find that you have your own unique way of handling things. I know it might sound hokey and not too soothing, but these times in your life offer you a great opportunity to feel, to know yourself, and to grow. Times of great tragedy and joy are magical and offer you a chance to get in touch with your inner powers ... and maybe get some new ones.
People report all kinds of psychic, psychological, and other strange phenonema during these times.