My best advice is to post this over at
https://www.indiehackers.com/. It's a great community of people who have bootstrapped businesses (and/or are in the process of doing so).
You sound pretty stressed, which is understandable with the kind of pressure you are experiencing both from within and from without. This is purely anecdotal, so take it with a grain of salt, but entrepreneurship is very stressful. It's unlikely you will find a soft landing making a sudden jump from a paid gig to supporting yourself fulltime with a new business (freelancing), while trying to build another business on the side which might not work out (your B2C project). That's not to discourage you, but a dose of reality which can help you look at things differently. For example, whatever you have now, just launch it. Launch it and ask people to pay for it. It will never be "good enough", and 12 months is way too long to work on an MVP before launching, because it never survives first contact with customers.
None of what I've said above is new, particularly wise, or even true in all cases. It's just the basic boring truth about entrepreneurship, it's hard, you're likely to fail, and you should've launched yesterday. That's why I like the indiehackers community, acknowledging the challenges above is an important part of working around them, which is a big theme in that community. Most are destined to fail, but not everyone does. So what smart things can you do to try and get yourself into the percentage that don't fail?
If you jump straight from having a stable income, to having absolutely none but with a family to support and without the ability to live off savings, you're not giving yourself a very good head start into an endeavor you're already most likely to fail at (statistically). Focus on what you can do now while you're still employed that will actually get you closer to making money from your product. The only real way to tell if you're getting closer to being able to make money from a product, is to start charging for it. ASAP. In whatever form you are able at the current moment, to people who really want to use your product.
Basically, I'm saying validate demand for your product, start selling it to people, market market market, sell it to more people, etc., and then think about quitting your job. Honestly writing lines of code correlates very poorly to making money in most businesses. Finding more customers for your product (and first finding out if they exist at all!) is far more important than building the product (until it's not, but at that point you should be selling said product whether it exists yet or not).
To your specific questions:
You quite likely shouldn't risk your family's savings on your business idea. What I think you're missing is that there are so very many options out there. Bootstrapping only means that you fund the business out of pocket. But making the assumption that you need to go broke to build a business is, I think, a mistake. Don't pursue a business idea which demands more of you monetarily, or in time, than you can afford to risk. Because as you acknowledged, there is always some risk. It's up to you to mitigate that risk by both approaching the business in a smart and focused way, and by picking the right opportunities to pursue. If you're not a billionaire, don't bootstrap a Rocket company.
It sounds in general like you're frustrated with where you are, and want to work on something yourself. Scratch that itch, 100%, just realize there are options to scratch that itch where you don't have to upend your life. Maybe pursue a job that gives you more freedom, so you can have both more time for family and your side projects.
Best of luck to you, there's a million people out there who feel just like you do.
Source: Im a fulltime freelance dev and wantrapreneur
Edit: See also this related thread on HN https://news.ycombinator.com/item?id=18438118