No it was an agressive strain of HiV that killed the partner. When Justin slept with Brian, Brian didn't know anything about the partner being ill. Justin just showed up on his doorstep.
I have no idea what the partner's name was.
Justin/partner were still friends with Michael and Ben, but lived in a house in NY...the partner may have even asked Brian to look after Justin.
The part you said above with Michael, I totally remember though. Brian did sleep in the chair.
I didn't finish it, though, so I don't know what happens much after the funeral...