I really like the serve at the apartment idea, though I am trying to make sure it's not just because of my intense dislike for this so-called man. But I like the idea that it will leave him literally nowhere to hide. If you do it any other way, I think his going to start trying to cover his tracks, and hide the evidence. Not that it would help him much, since you've already got it. And it might be fun to watch.
If he's served at the apartment it might just knock the wind right of out his sails, whereas anything else would probably take him down the deny and deflect road. And that doesn't sound like a lot of fun.
I can't get over the fact that he thought he could get away with having a apartment like that, and you'd never find out! Then again, he got away with it for a good while. But still.....