If you really wanted to move out, why didn't you use your tax return to pay the minimums on your credit cards and the rest to get the hell out of Dodge? Why did the whole of your tax return go to cc bills? I know you want your debt to be gone, but it's still not and you are still in this "toxic" situation. You did not think this through. Well, maybe you did, but you didn't follow through. IIRC, you had a plan a while back to "get out" when your tax return came. The whole thread about wanting your MIL to give you the truck/SUV when you left and whether or not it was ethical to bilk her for the back rent (which most people said was *not* ethical, but which you decided to do anyway)?
I don't think people are "on your back", it's just that you're inconsistent. You say you want to leave, complain, people here have supported you for over a year and you still make excuses to not leave. You talk about how your MIL is so toxic, but she is supporting you right now... with her own very low income. If you want her to fix the problems in your apartment, why don't you pay her rent so she has the money to do it? Or better yet, use the back-rent to do it yourself and call it even. It's just that you can't have it both ways. You're an adult now.
I really don't think you'll move out this time, either. You'll find some reason to stay, especially since your MIL is now retracting her order for you to get out and begging you to stay. She'll make some concession that you will insist you can't refuse and you'll still be where you are 6 months from now. I know you are a very, very young couple with the stress of two kids in a rotten living situation, but you need to find a solution. It takes maturity to ACT on what needs to be done, though. I truly think that you get something out of staying where you are and it allows you to complain about it. If not, then stop making yourself the martyr here and making your children the victims. Grow up and move on.
This is tough love. You know what you have to do. Do it, or accept your circumstances, stop complaining and make the best of it. Use your time on the internet to find a family shelter and spend the time there, where at least the conditions will be healthy, to save for an apartment. Good luck!