You are right, if he wasnt on the come he probably wont be cheating, but its one of them, u wont ever know..
Your in a crappy situation were if you leave and he does commit suicide, your obviously going to blame your self its human instinct, and i dont mean to upset you, but do you seriously think he did nothing with the prostitutes? And if he never he went to meet them for sex. Simple as. Im doing my best to stop coke im lapsing once a month and i cant stand the stuff. So i know how your husband feels and how awful the stuff is.
But my advice is.. is that you have a couple of options..you stay with him, he gets the help.. no more cheating and if he keeps relapsing your leaving.
Or your young.. do you really think is he going to change and you pack your shit now and move on and may be still support him. Your probably going to be looking over your shoulder all your life with him till the next time you get hurt.
Id personally have a good think what you want to do. Its not all about him. You need to think of yourself.