Dial right back until you're just dealing with priorities, clean, food, sleep.
Use the nightlight. At 4, her imagination is wild right now.
Get a reward system into place - praise even the tiniest of things, such as taking a cup to the kitchen, playing nicely for 5 minutes, anything they've helped you with. That positive attention sticks.
Don't sweat the small stuff - stuff like wanting to wear wellies on a sunny day or refusing to put a coat on to go out will have their own natural consequences, you just take more suitable shoes or a coat with you.
5 minutes timers for tidy up time - who can pick up the most toys in this time? Loads of praise at the end.
Guided tidying - a big mess is way too overwhelming, so break it down into simple achievable bits.
Tell them why something needs doing - we need to tidy things so there's more space to play and (insert favourite toy) doesn't get broken, as I know you'd be sad.
We sleep so we can grow and be happy, and it helps to make us big and strong.
Even now at 54, I'm better with stuff if I know the why!
Sleeping - simple routines, and if the 4 year old sleeps with you and you both get better sleep for it, then do that. It won't be forever. If you get just one night where she gets up less, acknowledge this and tell her what a good girl she is and inject a bit of a goal for her to see if she can do it again tonight, as you can see she's starting to become a big, grown up girl.
Ignore as much as you can where she's seeking negative attention where it's only minor stuff that doesn't matter really in the long run.
Proper down time, be it reading with them for ten minutes or they watch a bit of telly.
Be silly and fun with them so it's not always about what they are or aren't doing.
When you're dh is home, make sure that you get some time out fully. Could be a bath with the door firmly locked, a walk, exercise class, coffee with a friend etc. gives you a chance to recharge.
Apologise when you get it wrong. So "I'm sorry I said I'd send you to Grandma's when I was cross. I was very tired, but I do love you so much and don't really want to send you away. Come and have a cuddle".
You're right in the thick of things now, but it does get easier once they learn to sleep independently and control their emotions.
I hope this helps. I've 4 grown up kids now, including a set of triplets, and the above is all tried and tested. 😉