First I want to start with I am a cat lover and owner.
I didn't have a problem with my cat -- mine just ran away from the baby -- but slowly got used to him.
But, I have a very close friend that had the same problem, one of her cats was like mine - eventually got used to the baby. The other well needless to say, it acted out alot and all the time. Her only solution was to find a new home for the cat. They ried everything -- but I think it just boils down to each animal has it's own personality - some adjust well to change others don't But, I do know that did try to give the cat medication prior to decide to give her away -- I think it was Valium from the vet -- it was in really small doses though. It's the same type of stuff they give a pet if they are traveling on an airplane to help keep them calm in a stressful situation.
I really hope things get better - no one likes to find a new home for their beloved pet.
C.