This is such a hard place to be. I think you need to put them in bed and sit there and read a book, do a puzzle, sit and ignore them and wait until they go to sleep.
Staying in the room with their lights out but the hallway light on would give you enough light to do something. Then just sit there, wait them out. Note when they fall asleep or start looking sleepy. Let them sleep in the same bed if they want but they have to lay still. You have to find a way to do this, they won't start minding when they get older, they'll get worse.
Please consider calling Habitat for Humanity and filling out paperwork to get a house that is adequate for your family. The house payments should be affordable if not very similar to your apartment cost now.
Our Habitat for Humanity has several houses in our town and the payments are all below $300 per month. The family applies for a home. Once they get approved they start volunteering in the current homes. They build up a certain amount of hours of sweat equity, ours is 300 I think.
The family reaches a certain point in the hours and the nurture committee should sit down with them and discuss their actual home. We decided we would not build a home with less than 3 bedrooms. We would not build a garage because very few people use their garage for their vehicles, they use them for storage and they are messy.
Once they get to that point they are assigned their own home. They work the remaining hours on that home. They pick the decorations and what extra's they want. If they want wood floors or a certain color carpet or tile. The family should get to make a lot of those style of choices on their own new home. Then they get to have a house dedication and move in.