Going to be tough to avoid, she may have been contagious before she went to work. Wipe down everything with Lysol-type cleaner or wipes. Door knobs, faucet handles, stove knobs, TV remotes, refrigerator door, light switches - anything and everything you can think of. Wash your hands frequently/constantly. Try to avoid rubbing your face and eyes with your hands.

Alternatively try to figure out when she was exposed, estimate the incubation period, work out the most convenient (least inconvenient) time for you to be sick, back out the incubation period and at the calculated time give her a big smooch right on the lips get it over with.