How do I deal with a critical and disrespectful coworker?

Stop sharing your personal information with her. And if you realize that she is using mean words to express her jealousy, and you know that you are none of those things, then ignore them. If she is not the owner of the center, and you both report to a supervisor, you could always report this. But, I think would just tough it out and see how it goes keeping things professional instead of friendly. Now, this doesn't mean for you to ignore her, but try to avoid getting into sharing those personal things. And in all honesty, it's good for you to learn to do this now, because I guarantee that throughout your working life, you are going to run into many who gossip, say mean things, lazy, etc, etc, etc. You have to learn to give yourself criticism first about how you are handling yourself on the job, and once you have done that and maybe adjusted any annoying behaviors, then ignore the bs. Good luck!