You contacted 2 MDs and got orders from one. DOCUMENT the entire thing, including being passed from the 1st MD to the 2nd. Then document your nursing assessment
, and the fact that you ran it by the nurse supervisor who approved the MD's orders. Then document what you did. Basically, CYA!!
Regarding the other nurse, if it was me, I would go directly to the source and I would have at least one other person present. Stay calm, summarize exactly what you did and why (as above), read from your documentation if need be. Then ask directly whey she considers that you made a bad nursing judgment. Then be silent. Then conclude with, "in the future, I would appreciate you coming directly to me with your concerns, rather than spreading bad feeing about. I am open to constructive criticism, and I am happy to learn, but undermining my decisions is both detrimental and rude." Then leave.
I know others won't agree with me on this, but I can't stand this type of behavior and I'd absolutely have to address it.