With regards to this troubling language that keeps popping up:
"freaking out in a non-productive way"
"because of expressed hurt feelings"
"polluted her thing with her lover"
NOT GOOD. I dunno if you're aware of this but her continually projecting her guilt and in turn making you feel worse than you already are is NOT OKAY!!!! It has nothing to do with you being mature or not. If you are experiencing something emotionally and voice that to your partner their response should be to support you through whatever it is. Period. Not try to make you feel like shit when you already feel like shit. Like you're raining on her parade.
Who says that? Seriously?!?! I know she's not used to considering another person's feelings, and that much is obvious, but, really?!