The speaker addresses violence as if it were an old friend, and that choice sets the whole tone. Instead of simply condemning it, the speaker admits to missing it. The memories are physical and oddly fond: blood running down the face, its salty taste, "all the fun we had." That honesty makes the poem feel real rather than preachy.
But the friendship turns out to be a trap. Violence began "taking control," so the speaker had to end it. The short, flat lines suggest someone choosing their words carefully. Even now, the urge sometimes returns, and when it does the speaker feels "enormous guilt." Looking in the mirror, they still see the person violence made them.
The mood is quiet, regretful, and a little tense, as if the past is still close by. Yet the last line pushes forward: "I'm far better than I was." It reads less like a triumphant boast and more like something the speaker needs to say, and keep believing.