A.C.
Um, please tell me that your 2nd grader didn't use the term 'bitchy'?!??!!
If you had told her no necklace, that means no necklace in my book. I would make her take it off.
That being said, in general, I don't think that there is anything wrong with having a couple of best friends. I had many best friends throughout the years...often changing from one year to the next due to changing circumstances. It wasn't until nearly high school when I formed my most lasting relationships with other girls. I do have a male friend that I have been close to since the first grade.
I understand your concern in this day and age, but my bigger concern is why you're letting her do something that you've told her is not acceptable?
Added: Who is dwelling? It was a perfectly acceptable question given YOUR choice to word it that way. We only have your words to go by and it could easily be interpreted as your child using that term...especially when you use the quotation marks (even single quotes).