She used absolutes a lot. Things were "terrible" or "horrible". The house was "a disaster". It was never partly clean, or messy. It was either clean, or a disaster.
But the biggest issue was that her perception of the world, including her perception of what people were saying to her - what I was saying to her - was utterly skewed. Anything I said to her, she took in the worst possible light. A compliment that could be shaded negatively, was. If I told her I liked her dress, that was taken as my not liking her other clothes. If I told her I appreciated something she did, that was taken as my not liking anything else she did. Every once in a while I managed to figure out how to say something that was so clear that it couldn't be misinterpreted, and when that happened it was as if I were speaking Greek. The statement literally did not make any sense in her mind. It was fascinating to watch; there was actually a discernible lag as she processed, and figured out how to misinterpret, anything I said.
It was as if she had her own private version of English, with her own definitions, which were more black and white (and shaded towards the black) than the vernacular version everyone else spoke. In order to speak with her I had to become conversant in her version of the language.
After a while it really felt like she was gaslighting me. Anything I said or did, she took in the worst possible way, and then blamed me for it. It took an enormous amount of emotional fortitude to keep reminding myself that this was fundamentally not my fault. I feel tremendously lucky that I didn't become depressed myself.
Happily, she eventually did recognize that something was wrong and got help, and is tons better today. Bit what they say about depression is completely true: your mind is lying to you. I watched it happen. And the even more fascinating thing is that, although she now recognizes she was depressed, she still doesn't remember those times the way I do. Her memories are still skewed.
If you are suffering from depression, please seek help. And if you are in a relationship with someone suffering from depression, find emotional support. It isn't your fault.