Well, businesses come and go. Start ups come and go faster. Nothing tragic will happen if you accept that. I am sure you will find a job if you keep things in perspective. It is just business.

However there is no reason to panic yet. It is likely they will raise again.

Meanwhile you can use your energy to prepare yourself. Get your resume and LinkedIn put together. Make sure your personal finances are secure and can handle 3-6 months with no income (standard advice for everyone). Start inquiring about what other companies would be worth working for.

If you have a plan to handle the downside risk, this will be less terrifying and more of a business like decision of the merits of staying or going.

Once you can feel safe walking away then you can negotiate a better structure if you want the extra time. It is important to have the walk away plan as your BATNA when negotiating.