He gave you IMMORTALITY, didn't say nothin' about remaining conscious!
And while suffocation due to CO2 accumulation doesn't feel nice, HYPOXIA ON THE OTHER HAND FEELS AMAZING!
So:
step 1: shut off your oxygen feed and your suit heat
step 2: let the CO2 scrubbers do their job
step 3: breathe easy because you still have the ambient nitrogen mix component
pretty soon you're gonna feel floaty, dizzy, and giddy - you're gonna feel exhilarated, a real I CAN DO IT vibe - and then as a tingly and warm sensation engulfs your entire body, you will begin to feel HELLA sleepy.
then your immortal body will go into a state of persistent dormancy, preserved by the cold, purified by the radiation.
if you are EVER found (assuming you ever are... and if you aren't, you won't be in any condition to care!) and your rescuers expose you to an atmosphere your body can actually use, you will AWAKEN and be able to pick up however many days, weeks, months, years, decades, centuries, or millennia later, and resume living a life, even if it isn't necessarily the one you once knew.
And should you be abducted by the gravity of any celestial body you will feel pain unimaginable for however long your nerves last, stranded on something that nobody else will ever discover to live out the heat death of the universe in a constant cycle of pain (if you can regenerate lost nerves) or as a mangled sentient* meat pile (if you can't regenerate) all because you were given Immortality and not Invulnerability.
Assuming you haven't entirely lost your mind by now.
No. You won't feel pain if you're not conscious. What are you on about?
Also, you can see the Earth and Moon in the corner of the frame, he's not that far away. Probably in Earth orbit, or in near-Earth solar orbit. So the celestial body he's most likely to hit is Earth, which means he just wakes up after impact and everything's fine.
A blog I followed stopped posting two years ago, and their site is still up but they don't post anything to any form of social media that I can search.