Thank you all for your responses.
Florence - I do have a very nice well-meaning friend I can talk to here. But although she understands to a certain extent, she does sometimes make excuses for him based on cultural differences (they're both natives), which usually ends in me sharply replying that there's no excuse for abuse. Awkward silence. But I really think the majority of the population really believe it is only physical stuff which constitutes abuse. This was back when he was drinking so I don't deal with that anymore.
Despite this, she is pleasant company and a genuinely kind person. As I live in a village and she a way off in a town, we don't see each other often, but when we do, I feel like I would rather have a nice time instead of getting worked up about my situation.
So, we burned the drugs in the fire last night as planned. I was surprised he went through with it, even though he had agreed to do it earlier. I don't think he entirely understood what the point was, but I told him I had made a decision to move forward with a clear mind and make healthy choices for my life (I've let eating and exercise etc slip), and that tossing the drugs was a symbol of this for me at least. After the relative calm I felt in the past two months, I reacted very badly to his broken promise on the weekend, and I am embarrassed I am even capable of such behaviour. It was almost like a child throwing a tantrum, which is scary considering I never even threw tantrums when I was a child. It's not me, and I refuse to react like that again. Moreover, irrespective of what he has done, he doesn't deserve to have to deal with a crazed woman screaming.
I do realise that I will know if/when he drinks again. And although he knows nothing of my pain, he now knows what the pain of my leaving him feels like. As Pohsfriend says: "The pain of alcohol is so much bigger now than any other pain it might numb". So it's up to him. Hopefully he can make the right choice. As for me, I'm back to yoga and healthy eating.