NeedSomePeace.....since you understand the term mindfulness.....which is a huge skill of DBT, you might think about the skill of "RADICAL ACCEPTANCE".....sometimes we have to accept the way things were/are because there is nothing that we can do to change it. Radical Acceptance doesn't judge something right or wrong....it just is what it is & we accept it & "LET IT GO".

I use this skill a lot. There were things that happened during a trauma I lived through that I felt I could have done better to protect my mother & get her the care she needed....it was 10 years ago now. I realize that I did the best I could do....I have to radically accept that what happened happened. There is no way of going back & changing it or making things right or protecting my mother (she died soon after that of the cancer she had) & the police couldn't charge the home care person because in reality, I protected my mother so well that they didn't end up with the evidence that would have nailed her & put her into jail. Some things just are what they are & even if we replay it in our minds it doesn't change what happened, we JUST HAVE TO ACCEPT IT & LET IT GO.

Might be a good skill for you to look into learning how to do it.