13 Years Of Good And Bad

My husband of 10 years has made my life and now our young boys life unbearable and embarrassing at times. Sometimes his drinking binges ends up with him in trouble, fighting with me about non sense, days hung over on the couch being grumpy and depressed--straight up negative- and I am always the one getting him home safely during these drinking episodes because I want and need everything to be mellow and normal. He is consistently the most intoxicated one at most social gatherings. I finally hate these times and don't know what to do. He tells me it is no big deal and to chill out and he knows he drank too much and it won't happen again, he is sorry and he'll never be intoxicated in front of our 4 yr old--which he has been- etc. etc.
We are still together because he is a very kind and good person who loves me and his son but when the drinking binges start he is a straight up looser with a very bad attitude.
We/ HE has been through 4 pretty major drunken ordeals the last 5 months all of which have made me so mad and disappointed I am set to leave.
In the last 13 years we have known each other there have been dozens of over drinking episodes with him. Some really disturbing times when I was so upset about what happened and how drunk he got I left, screamed, attacked him, wrote him 3 page letters about how I feel and on and on but it always happens again at some point. Finally now I am not mad any more but completely over it. But confused.