I really dont think we should be trying to act as paranoid as an addict - the man was admitted to the hoispital and put in the psychiatric ward for weeks.
I think it is safe to say that they did a batter of tests; including not just urine test for drugs, but blood tests. I think we should not be doubting the hospitals credibility here. So for the sake of sanity - assume he was not out doing drugs those 3 days if she says the tests were clean.
From what I have read about cocaine and been told by my RABF - the use of it, and the withdrawl of it creates terrible lows, or depression. Its hard to say what happened to the man in those 3 days; sine we are going to now assume he wasnt using crack (a form of cocaine) - there other scenarios to explain his condition when he returned. i.e. no one even conisdered maybe he was drinking not drugging, etc.
But does it really matter anyway?
I think OP real question is going to be answered only by her views of the institution of marriage, and her acceptance that this patten on activity MAY never end. I disagree with those of you that say it WILL never end; that is the speak of the hopeless. It does happen. I dont think its wise to expect it to happen however. You cant base your life and its decisions on what might happen. i.e Dont go maxing out your credit card cause you might win the lotto Friday.
In my opinion, I would postpone the wedding; in your original post - you said you felt like by continuing your path and plans for the marriage - were telling him it was ok to use. Well, now tell him its not ok to use; and that you have been hurt. Send the sign that unless he does continue to get help and stick with it; that you wont be there in that future the two of you planned.