terrible twos??

Rebecca
My 2 1/2 year old has recently started throwing herself down, screaming and crying or even throwing stuff anytime she doesn't get what she wants to if I tell her to do something. It's not ALL the time but a lot of the time. I have a 3
Month old son but she started these tantrums before he was here. She gets more attention than my newborn does and we did not raise her that she gets what she wants when she wants it so is this just a terrible twos attitude or what? She makes me want to lose my shit which I know will not help the situation. How do u handle your toddlers when they act like this?