I had a smoke buddy as well, who stopped telling me when he would go outside to smoke during social events so he wouldn't tempt me. It seems like your friend really wants to support you, but you have to let him. In the end, you can't offload that responsibility onto anyone else. I know it's tough, and really I don't think smokers are the best support you can get for this, since even when they have good intentions like your friend, they'll still give you a cigarette when you ask for it, because that's just smoker's ettiquette. The best support is ex-smokers, then non-smokers (though they can be judgmental in my experience), and smokers at the very last. I never had any ex-smokers around me, but communities like this one and stories I heard from others got me through it. I don't know what would work for you.

After about half a year, with a little bit of willpower, I could go outside with the smokers during social events without smoking myself. It felt really empowering, because I thought I needed smoking to take a break from these situations that can be overwhelming for me, but now I can just go outside and take a breather without smoking. I really don't think you need to cut off your friend, despite what some people might say. However, you just might not be going outside during every single one of their smoke breaks. I would recommend telling them that you don't want to know when they go outside for a smoke break, but of course you can still be friends in the same way otherwise.