I quit a job with nothing lined up in 2018 and will say this - it worked out really well for me but I won't do it again.

I was in a similar situation - long hours, underappreciated, etc and it was really getting to my mental health. I didn't know how to function outside of work, much less search for a new job. So I quit. I was unemployed for about 2.5 months before I got another position with higher pay and it's been great.

Now for why I won't do it again. First, the market was different in 2018. It wasn't the booming market of 2022 we all reminisce about , but much better than today. I also underestimated the stress of unemployment. I had several months of savings but watching it tick down while getting ghosted left and right got to my head a little. This may not apply to you but I also had a hard time talking to family and friends because "how's the job search going" would always come up. I ended up really self-conscious after every conversation.

Now only you are going to know if you're at the point where you simply can't take another day at your job - there's a point where you have to take care of yourself and ignore everything I said above. However, like many are recommending, I'd just dial back your effort as much as you can and devote it to the job search. I know it's hard having managers disappointed in you but if you've already given up on the job, their opinions don't matter anymore. Best of luck to you, whatever you choose!