It is true and real that people in an altered state of mind from a substance or feeling often say and do things the under normal circumstances they would never do. It's also true that they can use that to diminish the pain they cause and feel.
This really speaks to me as I just realized something yesterday. When someone apologizes for hurting you with "I'm sorry, I was ______" they don't just make themselves feel less pained by their behavior.
What happened to me, was this: initially I felt, "Ok, it really hurt, but they didn't really mean it, they apologized so I'm gonna let it be." The several hours later something triggers it and the pain comes surging back like it was just said. That's when it hit me.... I was failing to fully experience that pain, because for some reason I rationalized that because of the circumstances of I was down playing it in my own head. Instead of taking it all right then and there, I shunted it aside, and then I had to deal with it all over again later.