How to deal with difficult coworkers?

I have one coworker who I cannot stand to be around anymore. I stayed home from work today because I’m so frustrated with her.

We were initially very close friends, until she stole an idea of mine, and I had to have our boss intervene to give me credit for it. Since then, we have both put a fair amount of work into repairing the friendship, but things have never been the same.

I don’t respect her as a colleague. She makes plenty of foolish mistakes regularly yet constantly complains about other people’s incompetence. She has emotional breakdowns about once every two months that involve getting furious and sobbing hysterically. She is constantly negative, and turns everything that happens into a crisis. But of course, nothing is ever her fault (she actually said recently, “I don’t make mistakes.”)

Lately she has done a string of small but insensitive things that have pushed me over the edge. I no longer consider her a friend, but I don’t think she realizes this, and I’m not sure if it’s appropriate to tell her.

The only solution I can think of is to work from home as much as possible, and come in on the weekends to do things that must be done from the office. There is also a room down the hall that I could move to, but it would probably cause a great deal of awkwardness for me to up and move away, when everyone thinks we are all still friends (and I genuinely don’t have a problem with my other coworkers, who I do consider close friends).

Any advice would be appreciated.