How do you deal with someone at work you don't want to deal with?

I work a 2nd job as a caregiver to the disabled. Tonight I have to deal with someone who is extremelly high-strung, annoying, and thinks she knows everything. I cannot avoid this person tonight, due to unimportant circumstances.

How do you calmly and coolly deal with someone who gets under your skin a lot? I can feel myself getting too emotional just thinking about it. Also, this is not an appropriate time or place for a confrontation.

I also go directly from this 3rd shift/overnight job to my primary, full-time job in education so the less I ruminate on this, the more I can concentrate on the job I really enjoy tomorrow.