How to be a better mum

Hey there to my Fellow Imperfect Mums ❤️
I'd like to here some strategies that you guys use to help keep you calm throughout the day. I am an exhausted mother to three beautiful children, 4.5 year old, 3 year old and 1 year old. I honestly feel like my day goes by with frustration, anger and exhaustion. A far cry from the perfect energetic, creative and fun mother I thought I'd be! My eldest two boys drive me mad to say the least. It's my eldest son who instigates everything and somewhat bullies his younger brother. There's always consequences such as time outs, naughty corners, taking toys away and the odd smack (and ear grabbing which I honestly hate myself for doing and regret each time I do it)
I don't know what else to do. I see the family of one of my nephews nearly daily and his behaviour is pretty crap which I can now see in my eldest boy.
My family life is crazy at the moment so I expected a bit of bad behaviour just until things get back in order and a proper routine is established, but meanwhile Im going cray cray! I actually wake up each morning somewhat fearful not knowing what my crazy little army have in store for me. My eldest is stubborn, territorial, demanding, attention seeking and is constantly bossing his younger brother around. My second son is loud, boisterous, sensitive and in the peak of tantrum throwing and doesn't like to cooperate in structured game playing (which my 4 year old thrives off)
We do group activities daily as its a time for me to actually calm down as when I am actively involved in their play, there's minimal issues between them both. It's the times that I'm busy doing housework, prepping meals and attending to my 1 year old do things get out of control which is let's say 23 hours of the day ?
Honestly thought I'd be much better at this. How do you ladies cope?