We have a written agreement, which I have absolutely no intention of breaking, that we are both to give 30 days notice. Him if he wants to move, me if I want him to move. I just don't know how to tell him so that it doesn't turn hostile, and he is NOT a nice person.

When I called him into my room before I confronted him about having sex while I'm home, he was bitching and moaning. Loudly. And I had to tell him not to ever talk to or about me that way ever again. So he doesn't take things well, and I hadn't even brought anything up yet at that point.

As for my dog, he's almost six months and he's going through teenage phases. So, there was biting, then jumping on counters, barking at the neighbors, one where he was scared of everything and everyone, and now he's throwing fits whenever he's in the kennel and I'm home. So he's yipping and barking, but its not often enough for me to seek help for it. I just ignore it, that's always been my approach. Don't give in and he will learn to stop.

But the roommate is constantly yelling at him. He told me he made a fb post about how he wanted to kill my dog, and a few people were suggesting ways, and then there was a huge shit storm because people were pissed that he would say something like that.

I can promise that if anything ever happened to Walter I would end up on Nancy Grace and in prison. And I'm not worried he would hurt my dog if I gave him notice, I'm just irritable that he doesn't have the patience. When I posted my room I clearly said there was a dog and he will make noise and probably bite you, and if you can't handle that then you aren't suitable for our apartment.

So that's that. I just want to live alone again, I just don't know how to tell him.

You don't have to answer this, but are you two sharing rent or is this a building supplied by your campus?

If you both are sharing rent~ I would have to say that you may just have to be out front and stern with him. Yes, things may get hostile and he may start yelling again- but it seems to me that he'd start yelling even if you were kind and 'letting him down gentle' per say.
Things may have to get worse before they get better.

If it's a building supplied by your campus- you may want to look into there roommate regulations and seek out authority to help get this situation resolved.

College is already stressful with some aspect. You don't need to go 'home' and be stressed about a roommate too.