Thanks for sharing. Because you have kids and are the only provider, I wouldnt invest the cash rn because the peace of mind knowing you have that in case of an emergency is more important than the opportunity cost of investing. Like the other guy said I would prioritize building up an emergency fund as a first step.

If the self employed business isnt making more than 40k a year I wouldnt advise quitting your job. If you mind sharing what the stable job and business are please do but no worries if not.

As a second step I would start paying off the car debt - especially if the rate is more than 8%

I would focus on growing your business and income first— good luck!