I know someone who does something similar to that, but he doesn't go until he's bruised; he just does it a few times, then manages to get his emotions under control.
Different story for me--if I'm going to hit/punch myself, or do that to something that can hurt me, I'm going all-in. I'll bruise myself, cut myself, or basically do anything that leaves a long-lasting mark on my body. I don't recommend doing it to that extreme, but if absolutely necessary, try to find a different way to cope. That's what my therapist told me, but it doesn't work for me. It might work for you, but then again, you're different than I am.