I'd have let the interviewer know, without details or trashing the woman, that you didn't like each other, and that you are fairly certain that she would not give you a glowing reference...supplying scant details if asked ("personality conflict" works well).
It's likely that if they do call her, and she gives a lousy review that you'll never know it...they aren't going to tell you that...just that they found someone else for the job.
I wish you didn't have to worry about it!!