Being a parent is a lot of work and of course a lot of joy as well.  Having to do it as a single parent is that much harder.  You are not alone, there are so many men and women who find themselves raising their children on their own.  I admire and respect you for putting your children first place in your life.
There are a lot of single parent support groups in many communities.  You might also want to look into a babysitting exchange program where people trade off watching each others children so that you can get a short break once in a while.
There are a lot of opportunities to work from home, but be very careful not to get roped into a scam that simply only wants your money.  There are so many of those out there as well.  Maybe you could do a home business of your own like pet sitting, daycare, bookkeeping, or working as a virtual assistant.  Each of these and other ideas would require marketing your skills or talents.  Try to access your current skills and think about what ways you might be able to use your talents to serve others and make money doing it.
Also if there is any way you can squeeze in time to work a job part time that couldn't hurt.  However I know that can be very hard to do if you can't count on other people to do you the service of watching your children while you are at work.   You sound very motivated and like a woman who very much loves her children.  Of course you do, you wouldn't be asking for advice, job leads, or ideas if you didn't care so much about their well-being.
Parenting is the most important job in the world I feel.  Unfortunately in the times we live, so many people are forced to parent alone.  And even when couples parent as a couple, far too few couples are able to keep one of the two at home with the kids as most two parent families today have both parents working full time jobs.
You might want to check out your nearest department of jobs and training office if there is one near your town.  They have many resources available to the public seeking jobs.   And of course there are all the many job sites on the internet.  And of course as you are doing now, you are using the skills of networking to reach out and find solutions.  I admire you for your courage to jump onto a blog and ask others for ideas, solutions, or thoughts.  Please feel free to email me if you wish to contact me or want even more ideas.

Best of success,
Joel