Passive Aggressive Conundrum

My roommate has outed himself as completely passive aggressive. Here's the issue: One of my kitties is prone to "marking" anything of large proportion that doesn't smell like Mommy (that's me). What can I say - she's a total Momma's Girl. I recall an incident years ago when she did so to one of my best friends who also has cats. There's nothing I can do about it. She's a cat and doesn't speak English. Unfortunately, she's decided that my roommate doesn't smell like Mom. So she's started marking his property. We worked out practicalities of keeping her out of his room and that's worked so far. But he also keeps his comforter in an "open" room. Guess what? The problem is, I can't talk to him directly about the issue. Oh, I've tried. But his reaction is to confront me passive aggressively. I get nasty text messages, complete with pictures. He posts shit on my Facebook wall. I know it's an issue. It must suck to feel that all of your belongings have to be quarantined from the "common areas." But until we figure out how to train kitty, that's just the reality. Not to mention, keeping a comforter on top of an end table probably isn't the best location in itself... I want to talk about these things openly and in an adult fashion. It's not comfortable but it's necessary. But when I try, he acts like I'm attacking him. If it's such a problem for him, well, then, move out. If you can deal with it and accept a solution that may not be ideal but works for now, well, let's talk. I just can't stand this passive aggressive B.S. I've given him pass after pass. I paid utilities on my own for a couple of months. I gave him a month pass on rent (which he's never made up.) I think I've earned some honesty and frank discussion. I don't know what to do. I want to post something looking for a new roommate, but I also know he's cruising CraigsList. It's a fucking Conundrum and what can I do to get out of it? I shouldn't have to work this hard at a relationship that isn't even a relationship... UGH.