Work on it in your free time while you work a day job to keep the $$$ flowing.
Also spend more time validating if people will pay for your product.
Good for you taking the leap, it wasn't stupid.
It sounds like you still feel it's a valid idea right? And you undoubtedly got more headway on the project being full-time for the recent months, so don't be so hard on yourself.
Go and get just enough contracting work so you can pay for your lifestyle, and keep working on it. Talk to your previous employer and mention you now have a couple of days free a week and if they are interested you could help them out ;)
Stupid is a bit harsh. I mean, your idea is not good and unlikely to make significant money ever. But there's no shame in trying something.
Just polish up ye olde resume and start applying for jobs. Nobody is going to fault you for quitting your job and trying something.
If you left your previous job on good terms, just contact them and ask if you can go back.
You sound like a nerd. Maybe you need a co-founder with more of a business background who doesn’t necessarily know how to turn on a computer.
You are short on cash, Take freelance project. With money in the bank you can think without fear.
Don’t try one idea, try ten. It’s like dating, you don’t have to always win. Market every day, twitter, web
In general, It takes 12 months before you have any noticeable traction. Find customers or people interested every day. Every single day. Build your followers