Just offering big, sympathetic hugs. OP, two of mine were total Death Wishers. DH and I used to refer to it as Kamikaze Watch. I remember going into the kitchen to pour the kettle, left the tea to brew, then returned to the living room to find DC3 (then 18 months) dangling from the tip-top built-in shelf (which reached the ceiling). That was a moment where I thought, "This guy's nuts and I just have to totally find a way of working with this."
You need to find ways of getting time to breathe. Nursery! Playpen.
Use less and clear language when setting boundaries.
Walk out of the room and ignore your DD when she's winding you up (as long as it's safe to leave her). Don't engage in the bad behaviour. They love a wind-up and your response means more attention. So the less you respond, the less attention she gets. When she's ready to calm down, play ball, and talk to you, then you can come in with the 'We don't run up and down the stairs screaming and throwing a ball at mummy's head," or whatever it is she's up to.
Save the warm, loving dialogue for warm, easy, loving times. But when you have to 'manage' bad behaviour, just be pragmatic, matter-of-fact, and don't engage. Don't get sucked into the vortex. Easier said than done. I have screamed into pillows several times, raising my kids.
You're in the thick of tough ages. I mean, society uses unicorn turds to paint a merry portrait of early childhood years, but f*ck me it's hard, OP. The pay-off is huge. But in the meantime, breathe!
Starting reception will help, OP. Starting school and the structure that comes with that environment helps, big time. Put the little one in nursery 2-3 mornings a week, if you can. You just need to breathe and make sure the house is secure (secure shelves/wardrobes/chests of drawers to walls, for example). Can you let your kitchen table become, as my Italian friend calls ours, 'La tavola della vita', the table of life? Our kids draw with Stabilo Woody crayons (they wipe off!) directly onto the kitchen table. And contrary to what others say, they never ever draw on walls or other surfaces. We can go to other people's houses and they would never draw on their tables. But at home, our kitchen table is there to be lived upon. I'll send you a photo in my next post. If you don't want to go this far, get butcher roll paper. Roll out a long length, sticky tape it onto the floor, let 'em go mad with chalk, crayons, whatever. Do you have a patio? Chalk! Another thing I find very calming is kinetic sand. It's messy, but it's very much therapeutic play. If you have any outdoor space, even if it's small, could you get something like a Little Tikes slide or Little Tike splash-about pirate ship? Something that just engages your little 4 year old. Something that is safe and thrilling at the same time. We also have this thing called a didicar. That's been a lot of fun and the kids can ride it up to the age of 8. Our kids just spin around on the back patio. My 17 year old even rides it. 
Hugs, Op. There's no quick-fix but there are tricks and ideas to help the days pass more easily.