I read this last night but didn't have a chance to respond before you deleted the question.
It's clear you want your children back. I have mine with me (still married) so I can't pretend to know how desperate I would feel wanting them back. Your post(s) sound very desperate.
However, they also sound irrational. You don't say how this situation all came about. I have friends who are single moms, whose exes have remarried, and they still have the children. I even have a friend who is a step mom, the mom has some mental health issues, but they split the kids 50/50.
They usually do what's best for the children - so without knowing what the deal was to lead to your crisis (I'm assuming this is a crisis for you, where you're considering such wild actions like quitting your job or marrying a gay man) it's hard to offer advice.
I would agree though that you could benefit from therapy. A rational, separate individual who can help sort out the things that are under your control (your attitude, your decisions, etc.) and those that are not. Blaming everyone else and society as a whole for your predicament means you've given up control. You can't change society or get your whole field to be less discriminatory. You can change how you deal with life. Therapy can be invaluable.
When we become a 'victim' of the system or in general, we are saying we have no say. That's a terrible message to send to your kids. I think you want the message to be to value truth, integrity, love, and acceptance - and so far, you're suggesting marrying a gay man, hoping to tear their dad's marriage apart ...
Hopefully you'll take away some good bits of advice from the moms here. You sound very hurt and bitter. That's not a good place to make decisions from. Lies, etc. only create drama. You don't want to raise your children with drama. Hurt people hurt people. So help yourself first. Heal the hurt. Really, that's where you should start. If you were my friend, I'd suggest the same thing. Then you'll be in a better place to decide what to do going forward.