Realistically you are going to have to leave the airport. You will not have access to international departure where all the lounges are, and the only lounge in arrivals is SAA which closes at noon (and you have to be a gold/plat or business passenger).
Domestic terminal is pretty much shut down between 10pm and 5am
What flight are you coming in on that lands so late? JFK gets in at 7am and IAD is here by 5pm if memory serves me correct.
Sorry for your loss