<human>: I've been living with "Kevin" for about a year now. From day 1 he never did his dishes. He cooks a couple times a week and utterly destroys the kitchen.

I cook a lot too, so I just got in the habit of cleaning up after him when I cleaned up after myself. We have a dishwasher so it's not that huge a deal. But he has not washed 1 fork in the entire time he lived here, and sometimes he hoards dishes in his room (all the dishes are mine but I let him use them) and will bring a pile of dirty ones into the kitchen. I don't know how he thinks they get clean...I wash all of them.

I didn't want to make drama in the house, he's a pretty ok guy and it's hard to find a good housemate, so I was kind of resigned to just doing the dishes. I didn't want to have to nag after him all the time.

Kevin recently got a new girlfriend, and in an effort to impress her (I can only assume), he actually did the dishes. But he did a terrible job. First, he put a bunch of dirty dishes in with the clean ones and didn't run it. Then, he ran the dishwasher overstuffed so nothing got clean. 

But more importantly, he washed a bunch of stuff that's not supposed to go in the washer. He put in a cast iron pan, a wooden cutting board, and a fancy knife I got as a gift. The pan needs to be re-seasoned, and the cutting board is destroyed (broke into pieces) and the knife is probably ruined too (rusted).

Obviously I need to have a talk with him. I was hoping to get some advice on how to approach it. Should I mention in some way the year of never washing up or just let that go? Should I ask him to replace the stuff he ruined? Should I ask him to just not wash up since I'd rather have dirty stuff that ruined stuff?

Summarize the given text in a few sentences.
<bot>: Flatmate ruined some kitchen stuff trying to wash it after a year of never washing it. How should I approach talking to him about it?