Hi Charli,
I think that was a step in the right direction, instead of blaming and excuse making your Beloved said simply. "I know".
When he is sober you could brink up the conversation again with him and remind him of his answer and ask him now that he knows what is he going to do about it and what can you do to help.
Its good you werent shouting, people tend to take issues more seriously when it is done quitely.
I think you need to make him understand that he needs to get some proper help or you are not prepared to carry on.
Good luck.
Suzie x