Oh for heaven's sake. Ignore the ignorance.
This is the scientific answer.
Herpes simplex A is also called 'cold sores' and other things. It IS originally caused by a virus. Once a person has that virus, it NEVER goes away.
Stress is a VERY common reason for it to flare up. During flare ups -- when the blisters and ulcerations are visible, it is infectious! Your mother should not share cups, glasses, tableware, kiss, or engage in oral sex during a flare-up! Flare-ups last anywhere from a couple of days to a couple of weeks.
Your mother should probably just make it a ritual to never share anything she puts in or on her mouth.
Also, your mother can infect her EYES. This is dangerous. Absentmindedly touching her mouth area and then touching her eyes could potentially cause blindness (rare, but it does happen). Regular and thorough hand-washing with antiseptic soap, and absolutely NOT touching the sore areas around her mouth will prevent infection transmission, and allow the infection around the mouth to heal faster.
Most of the time, when the word 'Herpes' is used, people think of Herpes Simplex B, or genital herpes. They are similar, but they are NOT the same virus.
People who have been infected with herpes simplex B face all the same problems as above, and are infectious to sex parnters. Herpes Simplex B IS a sexually transmitted infection. Herpes Simplex A is not.
People can catch Herpes Simplex A from casual exposure, such as taking a drag off an infectious person's smoke, or a sip of someone's drink, or by being touched by an unwashed hand!
I found some of your remarks unnecessarily condemnatory.
There is no cure. There are treatments available. The single most common cause for flare-ups of either strain of Herpes is STRESS.
Good luck to your mom. If she's a little careful, and adopts some habits, she'll be fine.