Can I not send my condolences?
Why won't you say your condolences?
She was a bitch to me.
You should say your condolences and not let personal feelings get in the way of it. You should care more about their loss.
I don't think I should.
How you feel in the moment isn't how you will feel about it later. Try to put your resentment aside for this instance and offer your condolences to her loss. You'll feel better looking back that you did.