Sod that. He's unwilling to change or try to, the OP has made that pretty clear. She said she's been asking for advice on his moodswings since 2010.
I suspect maplebaconchips is some form of a troll, IGNORE. After everything you have written on this thread, to say things like "it's just a bit of pot" is ridiculous. Wow, great help there.
He's being nice because he senses change, and that you're standing up to him. He's trying to distract you.
I do not advocate leaving someone on a whim. You have provided a lot of detail that shows the cycle. It is pointless to stay in the cycle for years and years if they are unwilling to get help. They have to want help. It's 2015. Does it feel like that's going to happen?
My ex was nice sometimes, too. He could be the nicest person in the world, when he chose to be. Don't fall for it. They will also pull out Mr Nice when they see you are dangerously close to having enough. I've been there. Breadcrumbs - another excellent way to put it. That's all they are.
But the yo-yo of my life nearly did me in.
I once said to him that I would happily go without his amazing presents or surprises if he would be consistently a nice person, and nice to me.
Living with the unknown is exhausting. Having someone be nice, and then treat you like you are worthless and stupid makes you feel crazy. Watching a dark cloud slowly descending and knowing that you're about to go through it all again, feeling sick and upset- and having it turn a good day into a terrible one. Getting in trouble at work because you're made so anxious by a bad scene at home and worrying that you are distracted, and no one really gets it.
The bad moods, the temper, not hitting you - but maybe lots of shouting, or hitting walls or punching tables and making you jump, not being able to say anything right as everything you say is wrong in his eyes, when he's in his dark place. The feeling that you shouldn't be in your own home, the feeling that you have to stay out of his way, or go away until it passes or something makes him happy (usually a delivery of a 1/4 of really smelly skunk.)
It's no way to live. It's certainly not a good place for children to live. I'm glad I at least got out while my LO was too young to know what was going on.