Gmod now crashes on startup

Long story short, after 8 years of the game working fine, Gmod now crashes on startup (During the blue loading screen) with a generic Windows error message. I had installed Kill Awesomium a few days ago, apart from crashes caused by it that had been resolved, it still ran normally.
I’ve tried verifying integrity (Which reverted kill awesomium), restarting Steam and my computer.
I’m gonna go through and delete a few addons at a time to see if they’re causing it - though, none of the addons I’ve installed or updated coincide with when this started happening.

EDIT: Think I’ve got it, it’s probably TF2 - I reinstalled it the other night, attempting to launch it has it crash on startup. Verifying now

Yeah, fixed by validating TF2