Anyone else can’t stand their 3yo?

My daughter is driving me absolutely nuts. I also have a newborn and a 1.5 yo. She gets ALL of the attention. She is in satiable. Yes I sit time aside for just her. I tell her all the time I love her. I put her to bed. I do special things with her all the time. But she is still just so awful. She never listens, she is SO rude despite my husband and I modeling kind behavior. I try my best to be patient and practice peaceful parenting but I am at my wits end. She also just decided to not be potty trained anymore and not poop on the potty. She is driving me nuts. It came to the point I felt so angry with her I had to leave the room. I also know I’m sleep deprived but I feel guilty but also still super upset with her. Am I a horrible mom? Please tell me I’m not alone. Any advice or words of encouragement would be helpful.