I'm at a total loss of what to do!

I have no idea what to do anymore, I'm close to tearing my hair out! 2 days of the week we have my partners daughter come to stay and it's really starting affect me and baby during the day and at night.

My baby is 5 months old and usually goes to bed at between 8pm and 9pm and then he will sleep right through till 9/10am but these 2 days it's completely ruined, he isnt able to go up to bed till 12pm because she can't sleep anywhere else except in the room with all of us, it takes her 3-4 hours to fall asleep so I have to wait for her to sleep and then I'm up atleast 5 times a night settling baby back to bed because she's coughed or whimpered in her sleep and that startled him because he's not used to it, and then in the morning she wakes up early and her dad just tells her to go back to sleep because he cant be arsed to get up, this happens about 4 times, waking baby up every time and then the last time when she decides she's gonna get up and go downstairs by her self to see her grandma she slams the door waking him up once again, so me and baby barely sleep! I've tried talking to my partner about it and he just says well you should just get up early with both kids, I've said multiple times that he has her 2 days he should be getting up with her it's her dad who she wants and I also give him a free pass and don't give him any baby duties on these days so he can spend all this time with his daughter so I don't think it's right I should get crap sleep and sort out both kids in the morning, she would be waiting like 30 minutes for her breakfast because I'm not gonna delay feeding my hungry baby 🤷🏻‍♀️

And during the day it's a whole other story, I can't go more than 5 steps away from my baby during the day, I literally have to bring him everywhere purely because I don't believe he's safe, she hits, kicks, bites people, shouts in the babies face, the other day while i was sat with them both she tried to play 'bang bang' with the baby which was making the baby hit himself in the face! And 9 times out of 10 she doesn't get told off for any of it and when she does she screams bloody murder because the other times she gets away with it, my partner thinks it's okay to leave the baby and his daughter alone unsupervised and has ignored my concerns so he's never been left with the two of them unless one of them is napping, and to make it worse she has a baby sister a few weeks older than mine at her mums house and she is allowed to literally do what she wants so it's a battle to teach her ways to be nicer as we are doing it every week and it never sticks 😩

she's such a lovely child when it's just me or someone other than her dad watching her but she knows she gets away with it when he's around and it's really starting to affect my mental health on these 2 days, I'm starting to dread it and I don't want that, I find myself making excuses to take me and baby out of the house, I'm at a complete loss, I just needed to rant really because when I explain all of this to my partner he just says I'm over reacting or 'she's only 2' I'm sorry but yes they pick up bad behaviour but she's had these behaviours for over a year with no improvement, but it's not her fault and I'm constantly reminding myself of that, aghhh i have no idea what to do other than just continue being secretly very unhappy and anxious because when I express my feeling I get moaned at like I'm the devil

Sorry for the long post I just needed to let it all out before I exploded