Putting flame suit on....
According to my schools honor code, if a student sees another student cheating then that student is required to report it or get blamed for cheating too. Quite frankly I think it was your study partners DUTY to go talk to the professor. It probably wouldn't have upset you so much if you WEREN'T involved - if you weren't one of the parties involved in the cheating (even in your minimal capacity). Now think about it ..... sounds like you were becoming a bit self-defensive ... making it HER fault and not YOURS.
Right now I don't think the professor could do much, since he did not specifically see the cheating (as far as I know). But..... if he did see it then he can give all parties involved a failing grade - so please don't ever do it again. It's not worth it.
As for the altercation - I wouldn't bring it up with the professor. If he feels that he needs to know, he'll ask you. Also - I'd get my grade back from the test first before considering talking to him about any of this. He probably will just watch the class like a hawk from now on. And you'll get out of the class just fine
Lastly, you really do owe it to your study partner to tell her you're sorry. She wasn't running off to the professor everytime she thought someone was cheating .... she did it after she saw MULTIPLE cheaters. Plus, if anything, you will be around her in future classes and clearing the air now will be much easier then letting it fester.
Hopefully you've learned a lesson here ..... keep your answers to yourself when you're testing but share info everywhere else. You're not helping the cheating student .... she's just getting through class and will end up in a terrible situation in nursing classes when she doesn't have an adequate background.
You'll get through this, just remember that things have changed with the professor. He'll be watching more closely ... so don't do it.
Ok .... withdrawing the wet noodle.
Plus ... just think only just a little bit more left till Christmas break.