Waiting to Exhale
centers on four women and their relationships with men and one another. All of them are "holding their breath" until the day they can feel comfortable in a committed relationship with a man. Waiting to Exhale: Information from Answers.com
There's also Urban Dictionary: waiting to exhale. (It's not what I would call usage examples.)
Waiting to exhale is figurative and it means that you are holding your breath in anticipation of the outcome of some event. I haven't heard it used idiomatically, but if you want to use it, here are some examples of when you could use it: waiting on exam results, waiting to hear if you got the job, waiting to see how your future turns out. Once you know the result, you can exhale, relax, but until that time you are waiting, afraid to breath.
Does that help?