Toddler Trouble

I really honestly thought that I would be struggling with the newborn in terms of our transitions. But how wrong I was! My real struggle is with Callie. The first couple of days we were home with Lucia were decent. But lately her tantrums have taken on new life. Our bedtime ritual, which was once my favorite part of my day with her, have become something I detest. She used to be so great about putting her toys away after her bath but all week she has flat out refused. At first I was trying to use storytime to entice her to put her toys away but even that didn't work. And I hate the idea of taking away reading from her. Definitely not the message I want to send about literacy. She kicks, screams and hits at Bill when he tries to help get her changed. She has probably had more timeouts in the past week than she has ever before.
I know in my head that the tantrums and the new lines in the sand are all about her being frustrated at the new changes in the house, namely the fact that she can't have me all of the time the way she used to. She loves to ask "Up? Up?" at the exact moment I sit down to nurse Lucia. Nevermind that my hands and lap were free for a good hour before that moment. Then when the answer is no, down goes her whole body smacking her head repeatedly on the hardwood floors. Pretty much my only saving grace these days is that she goes to my mom's on Mondays and Fridays. It is really the only peace we have at this point. I feel bad that I feel relieved when she is gone but it is just so hard to balance an active toddler and a mellow newborn. It could be worse of course, Lucia could be as high maintenance a baby as Callie was! I am really trying to imagine how I am going to handle this when Bill goes back to work and I really can't even picture it! I hope that eventually Callie will adjust to the new changes. I know I just have to stand my ground. They don't call it the "terrible twos" for nothing!
Otherwise, I am just going to have to find some shifty scientist who will agree to clone me!

Anyone with two munchkins have any words of advice?  This gets better, right?