Darwin2012, criticism is not easy to comprehend. And you are not a bad person - its my understanding that you may be struggling to keep your head above the water line.
Understanding that many folks criticise and it’s usually never to do with the person being victimised. So this is not about you ~ it’s about her fears. Your fears may creep in too – do you believe or even partly believe what she is accusing you of?
When you argue, she sees you as the perpetrator to her intense self loathing. It is projection and it could also be partly feeling invalidated. Arguing - don't engage
I can also suggest you have read up on fear, obligation and guilt. I found all these to be much of the reason why I reacted the way I did to my SO: Workshop - US: What it means to be in the “FOG”
and we have been arguing a lot
Arguing is invalidating for you both. To stop the bleeding and cycle of conflict – are you willing to try some new ideas?
I say such mean things to her and how I don't treat her as she deserves to be treated. She then said that she didn't like me and that I should sleep on the couch...I agreed.
Do you see how you response contributed to things going badly?
Can you share the scenario that lead to you being sent to the couch?