unfortunately, toxic people are everywhere. It is better not to get emotional and show your feelings. But ell them in a very matter of fact way, that you won't take their crap/ stealing/ lying anymore. But you need your good friends to call them out on their behavior too. Let them know that people are noticing. Chances are they have treated others the same way.

I have a large group of friends and everyone gets along except for two. As the saying goes, give them enough rope and they will hang themselves. People in the group started calling them on their dishonesty and they went away.

Good luck and be brave.