I do think you would be opening Pandora's box with any response to his "poor me" email.
Not sure why you feel the need to reiterate anything about there being help out there for his drinking issue, he knows there is and he continues NOT to seek it.
And besides, any suggestion of anything on your part will probably be heard/read by him as if he does X, Y or Z then you might re-think remarrying him. And if you state to him that even if he does X, Y or Z you still would not want to get back together then he would hear/read that as then what would the point be.
I'd just delete the email and I would think about getting yourself a new email address and deleting that one.
Happy Easter.