Gah, mine left and came back more times than I could count and after 3 years of the tired game I finally had enough. Just ask yourself if this is what you want the rest of your life to be like. Mine was the same way, always found some way to sweet talk himself back into my life until the next a*hole episode.
Carrying around anger is not a healthy thing, but neither is being trapped in an unfulfilling relationship. Can you cut him loose for a while? tell him you need some space. ;-)