Discorde
Are you serious? Time of usable conscience may be only 30 seconds. Descent immediate and tell ATC to sort their stuff out if you have the bandwidth. A Mayday with pressurization issue will do. The chances to bang into another plane from 36000 feet to 10000 feet are in all cases low compared to assured death in less than a few minutes. If you have an approved working Oxygen and some redundancy with a second pilot with a second mask and checked O2 flow is a different matter, but in the case of the accident plane an immediate descent is in order. Set the AP to 10000 feet in case you faint and will wake up later. It is similar to an engine failure in a single, You sort first out and make a plan how you get away in the most survivable way and then you talk to ATC.
The wife of the pilot Juliane was on board too and holds a CPL SEP from 1993. Why neither of the two pilots on board where seen in the cockpit remains a mystery. She was not certified for the plane but definitely able to do a descent to 10000 feet.