open old wounds
To bring up or remind someone of a painful, tragic, or unfortunate past event or situation. Seeing Jessica with her new girlfriend opened a lot of old wounds this afternoon. The fight got pretty nasty, and we both started opening old wounds from years ago.
open old wounds
or reopen old wounds
If something or someone opens old wounds or reopens old wounds, they remind you of an unpleasant experience in the past that you would prefer to forget. I didn't raise the subject again — I was in no hurry to open old wounds. It is said that the row is reopening old wounds among Conservative MPs.