As you are asking for advice here, you didn't say if they are for future jobs with other companies or what could you do in this case (such as trying to get your job back)?
As the current job situations are pretty bad, my personal advice will be working toward the latter case.
Write your old boss a detailed letter, explaining to him/her what exactly were happening. Make sure you don't place blame on your coworker (even if we know she was at fault to protect her turf) in the letter. Make suggestions to your boss on how to improve the office procedures so that no one would have misunderstandings on how to do their jobs right. For example, asked to have procedures documented, create daily to-do list, and at the end of the day, asked to have peer-to-peer review (even better with your boss presents) of the tasks you have done at the end of the day. If your co-worker has any intention of sabotage you, it would be very obvious during these review.
One thing you need to understand is your boss probably aware what was happening but choose to keep her because she was there longer and know everything and your boss depending on too much.
Tell you boss you really like your job, and that you are willing to learn and improve the company.
These are only some of the things I could think of right now, and others are welcome to add more comments.