Everyone has something from the past that they like to dwell on in the present moment.
This practice does nothing to you except stalling your brain from accomplishing wonders.
The past is gone. It's over. Why ruin your present and the future thinking so much about what happened to you some years ago?
You can't change what has happened. We haven't invented the time machine yet. Accept this and move on.
Focus on what you can do right now.
If you have to reminisce the past, then make use of it by recalling the experiences which taught you something about life in some way.
Let other memories, like a bad breakup or some bad treatment in the past, go down the drain. They don't fit in your present luggage.
Let go of any past baggage, whether it belongs to you or someone you're close to. Your present will be a lot better.