Wow .. yeah thats a lot of thinking you have been doing today..

Of course anything is possible .. The only thing I would say you might want to look closer into is the following...

~ Since for the time being you are/have been estranged from all 3 of your children... Could you be thinking about having another child that NOONE can keep you from raising as you want.
~You mentioned finding a Man and having some sort of contract drawn up to assure financial support??? That's all fine and good but there is no way to guarantee support from anyone... I know people rich and poor and trust me they are not always receiving child support for a variety of reasons.
~ You said it would be 20 years of hard work but you would end up with a meaningful relationship ???? Just because you raise a child from infant to your adult doesn't guarantee a great relationship.. Same as your current relationships with your kids won't neccessarly mean the relationships won't improve.

Again anything is possible I'm not being a downer here ..

Just some thoughts...