history: A few months back I make serious mistake during an experiment.  Thankfully it didn't actually destroy the work.  I am still super embarrassed thinking about it.   I was so embarrassed at work last week.  My boss keeps bringing up a mistake I made months back. That happens_comma_ you have to acknowledge mistakes to learn from them.
current: I did though, I've apologized repeatedly.  we've discussed it multiple times.  It's hard because she brings it up in front of others. 
next: Oh well that seems improper, you should bring it up to her supervisor.