Hi there, I did the exact same thing as you (at Google Sydney), before eventually deciding that I must strike out into the wilderness. In the few years since I left; I worked as a solutions architect managing a team, a team lead, a remote dev, and now in a startup. Front-end, back-end, flip-side, all the ends. So I've been deliberately trying different angles of my career to see what suits. I'd describe this process…
"If you stay at Google, make the most of it by progressing deliberately in your social life. If I'd've stayed, I could have comfortably raised some kids with my wife by now - but that's still on the todo list." THIS all the way. When we are young, we think that we will be remembered by the company that we worked for and the people that we worked with. The sad truth is that in 99.9999% none of those people will rememb…
The latter arose from my chronic depression and the lack of ability to create any long-term social relationships which are not based on professional interaction. I have never had friends outside of "workplace buddies" mindset for all my 33 years of life. They were lost instantly when I left the job. I've managed to find a way in remote consulting which lets me pay the bills and have some food (I quitted drugs cold turkey two years ago). But nothing hits you harder than a feeling that it's all over and you are tamed with your loneliness, the only thing that is left is your aging you don't want to face.
I can give no word of advice to you, but I want to say that I feel you. You are strong, don't let 'em get you this easy.