Getting away from the 'is it a hobby' discussion and reacting to your situation.
It appears from what you've said that actions of yours have hurt your SO. I'd guess you cheated on her, and you've lost her trust. If you want to save your relationship, it's time for you to give up all thoughts of non-monogamous sex. I know, that's so tough, you can't just wipe the subject from your karma; but you must disguise it thoroughly for your relationship to survive.
Immediately, get off all these sites that are to do with non-monogamy! She feels that if you access these, you're cheating again. In addition, accessing these brings your mind back to what you should be avoiding. With her, walk away from 'virtual' discussions - have real ones instead. I'd also start a new, non-sex driven hobby that you can share with her.
If you can't do this, it's probable that your relationship with her will suffer and quite possibly end.
I wish you the best of luck . . .