[fezzl]

Then your problem is that you don't have a business model (much less a validated one), not that your traffic is falling. Even if your traffic is growing as before, you need to be similarly worried.

Get your business model figured out as quickly as possible, and cut your expenses like hell in the mean time. Get cash coming in from other sources at the moment (does not need to be from your startup). Hell, slap on some AdSense on your 200,000 uniques/mth site.

Honestly, quitting and going back to a job because of this little "setback" that still nonetheless leaves you at 167,000 uniques per month is pretty cowardly.