Hi Chamomile,
I have been where you are and I feel for you so much. Two things I would say which are oly my personal opinion.
1. If you feel you can’t take any more then yes you have made the right decision for you at this time.
2. Just because you are ending things now doesn’t mean it has to be forever. If he is as he says serious about getting help then that will help him and you may at a later date be able to rebuild your relationship.
The only other thing I can say which I am sure lots of others have/will say is take care of you. You can’t do it for him. As part of taking care of you if he has asked you to take care of finances do or you may find there are none left aside from the obvious temptation for him.
It is not any easy choice, 7 years on I don’t regret my choice at the time at all and my life has improved as a result but shutting the book for me wasn’t the end of the story but eventually was the start of a better one. I hope you find some space to look at things clearly and be resolved on your final decision one way or another, Lilly x