It certainly ruin their mental health and physical health! It is a devil! When they are on it, they are just not them, it is just a selfish and terrible person, who doesnt care about anything. And I also hate the after effect. I can imagine it took a lot for you to make a decision to break up with him.
For me, I just havent made up my mind to give up on my husband. He was clean for 8 weeks and slipped. he told me this time he didnt enjoy as much as usual. And he just will do it. He went back to work yesterday after weekend drama and nothing seemed happened.. I trust him as my husband, but of course i dont trust if he is on it. I still want to keep our kid although I am worried.. perhaps I am so stupid, only thing I can do is wait and see for now.