Maybe a silly question, but did you show/state/mention your shock at this outcome. After all you did say you thought it was a way forward to develop an action plan. Can you speak to someone - HR maybe - and address this? State that you had no warning of this and it has impacted on you in such a way that your relationship with other colleagues is suffering as are you.

Sometimes these things do come out of the blue and we are not or cannot ever be prepared for it. I suggest if she is that difficult to work for that you start looking out for something else. I personally could not work in that environment and would dread coming in every day. Now that the situation has been turned upside down, sometimes you can never get back to where you were.

I am sorry for your situation but the only way you can deal with this is to get transferred or get out. There is no point staying somewhere if you think management have it in for you - why suffer - your health will in the end.

If she now has to answer for her mistakes maybe you could bide your time and see if things improve or if she even decides to move on.

G