>>1 first off, you were right. If she had at least liked the picture then that would have been fine, but she didn't credit you and it took you hours of effort, that's wrong. Hard work is hard work and you have every right to be credited for it. You said it nicely and politely so you aren't wrong. But maybe you should talk to your friend about it in person and tell her that that picture took you a long time to edit and that she could at least credit you for it, it hurt your feelings.
The whole frenemy-mean-girls situation....I've been there and all I can honestly say is that that kind of life was such a terrible waste of time. Ask yourself if she's really worth having as a friend? If she isn't then maybe you need to find new friends this don't fight with you over stupid things. If she is worth having as a friend then it's your duty to put up with the crap of her other friend, that's just how these things go.
You weren't being an attention whore at all! That girl was the real attention whore for starting such a petty argument! It's best to delete and ignore those kinds of comments because they can turn into harassment very quickly...
Anyways good luck with the situation! I hope that I helped~! :3