My new dog is territorial of my other dog's stuff after 2 days?

i just got a 9 month old shepherd from a shelter. They told me she was high energy, good with other dogs and loving. I played w her there and loved her. I brought her home yesterday. I didn't slowly introduce them bc my older dog bruno loves all dogs but now my new dog (who also starting this morning has been throwing up and lathargic.. Great) snaps at bruno whenever he comes near her. And sometimes leaps up to snap at him when he just enters the room! I always say NO and let her know its not ok but i don't know if i can keep a dog who isnt nice to bruno. Its not fair. I guess i just want to know if this is just a getting to know eachother thing or if she's just not a nice dog. Ps. After i already owned her the human society told me she was brought to them bc she killed a cat. :/ idk what to do...