My problem, or his?

I'm new here. Well, new to posting anything here, but today has just been so miserable that I had to put it all somewhere, and I hope you'll all be gracious enough to allow me the vent. My other half is eight years younger than me, and was diagnosed with ADHD and depression as a child. His mother died when he was young, and his father refused to get treatment for his problems, insisting that he was making it all up for attention and because he was lazy. I know he still suffers terribly from ADHD, and he's acknowledged it himself many times. The problem, I suppose, is that I don't like who I'm becoming.

I've turned into a nagging, resentful and miserable person, and I hate it. I ask for him to do things a million times and nothing is done, or I have to blow up and cause a giant fight for it to get done, which I then feel awful for and spend a day apologizing. I'm resentful of the times that he's been violent towards me (years ago, before he gave up drinking, not an excuse I know, but it is what it is) and I'm resentful of his use of cannabis which he says is the only thing that helps him deal with his hyperactivity. I've seen him cannabis-free, the hyperactivity is vast and incredibly difficult for us both, but surely there's another way?  I'm miserable that I never get to say anything that he doesn't like, make a point without being talked all over, get any of his attention without having to force it, and get blamed for anything and everything in giant stampeding shouting marathons that I'm apparently supposed to just sit and take without speaking.

I'm making him sound like the worst person on the planet, and he isn't. He's a wonderful guy, my best friend, and I love him unconditionally and will support him in any way that I possibly can. He's attempting to get himself off the cannabis, and to be frank, some days I really just want to shove a joint in his mouth and tell him to shut up, it's HARD. I hate this, and as sickened as I am by thinking it, sometimes I really don't think I can take another minute of this instability. How do I approach asking him to get professional help? I've tried before, but it ends up in a days-long fight or worse, a weeks-long depression. Everything I say he seems to take the wrong way, sometimes to such a degree that I can't help but think he's doing it on purpose. I've never known anyone so overly-sensitive in my life. I've no intention of leaving him, I love him too much, and I believe completely that he loves me, but I'm so lacking in energy and motivation to keep fighting, when do I get to take care of me? It feels like all I ever do is Care and Understand and Accept and Adapt.  Does anyone have any advice?