Bella,

Your supervisor is being a Mensch.

Your coworker who did what she did, trying to get you fired under the guise of "helping" you, was being a jerk.

Her behavior, and especially that part about her trying to "help" you, is indeed aggravating, but look - your supervisor is being a Mensch.

Why did you draw that conclusion about not trusting ANYBODY if you saw, for yourself, that your supervisor is a good person?