Im sorry for what you are going through. I have a similar story. I cant really offer much advice and im a few months down the line from you in that I found out in February. I heard all the promises to change and denial of needing professional help. Hes now (june) finally attending a rehab programme but the damage that was done to our relationship through all the months of lies betrayals and blowup arguments over the drugs has completely broken our relationship and hes actually left me.
So just be careful, now that you know you are in a strong position to be able to walk away if necessary. I know i had rose tinted glasses on when I fiest found out as I assumed ah him telling me is his cry for help and a sign he really wants to change but I couldnt have been more wrong.
Be careful, look after yourself first.
Sending you big hugs