My startup failed and I got a job at another startup, and now I’m miserable. I spend the whole day sitting in front of the computer, and I can’t stand it, it’s too boring. I hate days, and I can’t sleep at night. I don’t know wtf to do.

You are Exhibit A of why employers (or startup founders) don't want to hire ex-founders, and if they do bec they need the skill, they keep looking over your shoulders everyday,

Take this job as an opportunity to prove them wrong. You are doing this not only for you, but for ALL OTHER founders who will need jobs soon once the bubble bursts and the angel money goes away. Be proud of blazing a trail and do the best job you can do every day, Who knows, maybe by showing excellence, you find your future partners and network for your next startup in a few years.

Perhaps you should find an earlier stage startup? Not one where you would be a founder, but a very early engineer that both gets paid and can help shape the company.

When you were a kid I'm sure you had other ideas on things you would like to do. So do it.

You obviosly are a person who needs to be at the helm of change. So do it and be proud of your past, the fact you started a business is something not many people do.