I’m so tired of this 😢

My almost 4 year old daughter doesn’t respect me at all. I’ve tried everything from gentle parenting to other styles of parenting. I’ve tried everything. She’s yells at me all day, constantly tells me no, everything is a fight with her.. all.. day long… everyday. Until her dad comes home and she immediately changes. What am I doing wrong? The only thing I can think of is maybe she’s mad at me or jealous about her new brother getting more attention. He’s only 6 months so he requires a lot of attention and I do my best to set aside alone time with her too but I’m only one person.. I’m so discouraged, feeling like I’m totally failing as a mom. I just wish I could have one peaceful day with her. I tell her I love her everyday through out the whole day, even during her fits. Idk what to do anymore. Please no judgment, I’m my own worst critic already so anything you say I’ve already told myself. I just need encouragement and maybe some advice. I cry everyday and I am so mentally drained. Im tired of being the “bad cop” all day long, everyday. My husband gets all the kisses, hugs, loves. Wish I could get that too for once.

Edit: I talked with her about new house rules and consequences. Time out for 5 minutes if she breaks any of the rules and an added minute to time out if she throws a fit during time out. Wish me luck! She is stubborn. Pray for my sanity.