How do y'all cope?

I've a newborn of 9 days and a toddler of 2½ years old . How do y'all cope when your toddler just decides to have tantrums , meltdowns , not wanting to listen to you , not wanting to go school? My husband is on paternity leave till end month and I wonder how I'm going to cope. This past week has been easygoing with baby but toddler has been showing some tantrums and doesn't want to go to school. 😭 It's so difficult now to wake him up even though he sleeps at 10am and has to wake up at 8am. I'm a c sect mummy and honestly, I feel like I need more time to heal. Im not even doing confinement like I planned to. Toddler doesn't seem jealous of sister as he's quite involved in everything concerning her. We include him when we're doing things with his sister. Just that now , it's difficult for me to 'control' his tantrum. He used to listen whenever we ask him to keep his toys / shower / wake up. But now , even a simple task of keeping his unplayed toys is a nightmare. 😮‍💨 Is this just a phase ? Can mummies share with me on y'all cope on days yr kids have meltdowns? I don't have any extra help from family members and I have zero friends. My routine is the same old every other day , wakeup , breastfeed, nap , settle toddler , settle baby , house chores , cook etc. I'm home all the time and sometimes I feel like my mind is going haywire especially if toddler throws tantrum. I dont want to scold him but at times I can't help it. Need advise 🙏😭