Rehashing old events

Could you help me with a strategy to get over old situations once and for all.

Often something will happen that will remind me of a past event and I immediately get triggered. I start to replay the scenario and then have full conversations in my head of what I wish I had said or what I would like to say now. Not surprisingly, this sets the tone for the rest of the day.

What I want is to be able to think of these times with a totally neutral mindset. And eventually, not even remember the events at all.

Can I put “thinking about the argument I had with Peter” in the C line? Or should I put “argument with Peter” as my C, even though it is in the past.