Got my period at work and my boss was unfair

So I'm at work and my period starts luckily I always have tampons !!! I got very bad cramps and I saiid to my boss if I could rest for a minute !!! She said "what a crappy excuse to not work do I pay you to sit " ! Now my boss is a woman who is thought would understand the pain but no the whole night she just started telling other employees how lazy I was being !! Is this right or wrong ??