What comes to mind when I read what you've written ChickChicken is an image of a woman living life in a bungee run who's just been given her first pair of scissors and is now thinking "dare I".
Your Mum clearly isn't very supportive. You're probably used to being told how you'll never quite make the grade. You probably believe it a bit. That's probably why you've stayed with your DH so long, because if being undermined wasn't normal for your life you would probably have identified this relationship as not good for you a long time ago.
They say depression is frustration turned inwards. What's frustrating you? Seems pretty apparent your ever-critical DH and Mum would be high on the list eh. I had a Mum like that, until I wised up. I've been free for over 8 years now. I highly recomemend it in the long term.
As an adult you have sole responsibility for the choices you make. Sounds obvious doesn't it, but now expand the principle out. It means he takes drugs because he chooses to. It means you can't make the choice to quit for him. It means whatever your mother says on the subject, the quality of your parenting is in your own hands. It means if you don't want to be treated this way you can't change the people doing it. It means you can walk away if you choose.
It's very, very scary, cutting out those people around you who just aren't actually on your side. Even worse when they've been huge figures in your life. Like I said, I've been 8 years mother-free (halellujah). Even now I sometimes still cry because I want a Mum, like everyone else. But I know deep down that I can't have one, because my mother isn't going to be a Mum. And I know deep down I had to cut her out of my life, no compromises (she never respected them long). If you want to ditch your husband then I wont lie to you, it's tougher before it's easy, but what worth having isn't? Every day people who hated pregnancy decide to have a second child, kids go to Uni knowing they're wracking up a 5-figure debt and spending 3 years eating beans on toast, even learning to drive is flippin' terrifying... We do these things because we know in the end we'll be glad we did.
When I picture you tied to that bungee-run I see you already have the scissors.