How to deal with toxic work colleague?

I’m a Teachers Aide and the classroom teacher I work with is absolutely toxic. She’s over the top sickly sweet to my face but other colleagues have mentioned her bitching about me to them. Apparently she has been saying that I’m not as good as other Teachers Aides because I’m still new to the job and learning. Pretty much saying I’m useless so my confidence is at an all time low.

How would you guys deal with this? Should I confront her tomorrow? I’ve honestly never worked with someone so negative and horrible, so I’m unsure how to tackle it