Partner cocaine issues anyone?

my other half of 7 years (2children) recently told me he has a cocaine habit of 5 years (on and off)

how have I not noticed this??!!!

he is an great dad, loves our girl undoubtably

he works hard, the bills are paid and we have a lovely home which he has put alot of time and effort into. 

He didn't have a great childhood and when we met he was abit crazy and did go off the rails on the weekends and I knew he dabbled abit but he really had calmed down and it was such a shock to hear that this has been going on so long. He made this out like a big confession and said he was going to change and all sorts but since then I have tested his urine in the toilet and it was positive to cocaine. (I know abit extreme but I knew if I had asked him he would have been offended that I was asking to do such a thing and I truly expected it to be negative I just wanted some reassurance

really dont know what to do I really love him and want a future with him but don't want him doing cocaine! It's so frustrating as he makes out its not a big deal sometimes but I don't think he will change 

any suggestions please