Hello Nicole and welcome.
Have you ever considered making a doll(no,don't do that) or locate a picture of her and( no,don't do that either)......
I know it's not a laughing matter and I can relate.
There are tenants above me that smoke drugs(which ruminate in the hallway),while their children are running and jumping nonstop,as they have ADD.
If this person won't let up on you,then may I suggest writing in a notebook(which should be left at work,for all intents and purposes)?
Get it all out of your system;how she makes you feel,etc.
In a separate section,you could devise a plan to move out.
You can also consider putting up a calendar,then crossing out the days until "Project Move" can be put into effect.
Don't allow her to replace your sunshine with rain.
Working and volunteering and finding time to workout;good for you(kudos)
Before you know it,February will be here and you can say good riddance to her forever.Chalk it up to experience and try to tolerate her as best you can.Try to view it as a preparation for what life has in store for you in the near future.
We never stop learning and if we can pick up a few jewels of wisdom along our travels, then we can be better prepared in the future.
The only thing we can actually change about people is our reaction towards them.