Update
Well... Turns out T will not be coming back. They took him to County Hospital and put him on suicide watch that night, and then he was transferred to juvenile hall the next day. Apparently he called several times during the night begging to come home, saying he'd "never do it again". Chris was having none of it. Which, I hate to say, for me is a good thing. I can't live like that, and he's not my kid so I shouldn't have to. And I told Chris that in no uncertain terms - that I'm *not* staying here if he comes back. Looks like he's in trouble for a couple of burglaries so he may be away even after his 18th birthday, so depending on the outcomes there, I may or may not stay here- I haven't quite decided yet.
Chris now both sleepwalks and talks in her sleep, but I'm no longer too worried about actually being in danger, though I'm still a little jumpy when there are loud noises around the house. I'm about as unpacked as I'm going to get for a while, I've got boxes in the attic of stuff I don't need right now, so if I have to move there will be only about half as much to do.