Stoic advice: how do I deal with unhappy memories?

B. writes: I would like to ask what do you think Stoicism has to say on the topic of ruminations over unhappy memories. I, as probably a lot of people, tend to randomly remember such, and sometimes it takes me minutes to calm down. I know all the reasonable answers like: you were a child, you couldn’t know better; no one remembers it except you; even if, it doesn’t matter; we all have learned our