Don't worry Ash things will work out fine for both you and Chewy. Hopefully the behavorist will be able to help you guys out with the little guy and things will get better.

I have a friend who got married a couple of years ago and moved in to her new husbands huse with her dogs and his two dogs and there was problems with one of her husbands dogs trying to attack her and her dogs but from what I understand they've come to a mutual understanding (the dog and my friend) the dog is never in the same room that she's in, if she enters he leaves...maybe you can try to get something like that to happen with Chewy and Teddy.

Anyway just know that me and the puppers are thinking about you and Chewy and praying that everything will turn out all right.