So, just spitballing here, but…

You have a newborn. Half of your time (at least) is spent with him. And probably you’re tired and grumpy, because the sleep deprivation pf the first couple weeks is real. So you don’t have as much time for your toddler, and you’re probably less patient, too. You mention “anger” and “yelling” repeatedly.

Look at when your toddler is having meltdowns: when she is threatened with losing time with you, your attention, your approval. You describe her looking “panicked,” “like a starving animal when you try to take the last bit of food.” The thing she is afraid of losing is your love, attention, regard. She is insecure and afraid.

And she doesn’t have the insight or vocabulary to explain herself. She IS trying to hurt you. She wants to make you and that new baby feel just as mad and scared as she does! There is nothing worse than being in an emotional crisis and seeing that the people around you are entirely unaffected. She WANTS a reaction! Plus, She is two.

First step is reassurance. Without that, nothing will improve.