Hi Swimmy,
I'm so sorry this is going on!
You've been through so much with the long separation, the holidays are coming up, finals ETC! Now deffinetely wasn't the time for exposure therapy! You knew this, or at least that the exposure had to be at your own pace. I think t should have trusted you on this.
I agree with antimatter and others, that as hard as it is you and she talking is the only way to fix things. In my oppinion, she should remember too that you're living at home with family that doesn't support you and causes more stress. She really is your only support.
Have you ever thought of joining a support group for those with OCD? Or really any mental health group? When I went to DBSA, there were a lot of people there with OCD and they seemed to really understand and support one another. This could help you too.