Help with Demeter from Cats?

I've been cast as Demeter from Cats in the musical, and I'm struggling with Grizabella The Glamour Cat. I just can't look sympathetic enough to make the audience feel the same. Any ideas on the body language I can use? Especially towards the girl who plays Bombalurina, we just start giggling when Grizabella starts looking emo. How can I stop laughing?