If they take 50% and you 50%, the only costs are for clothing they might need that is shared.
When the kids are with them, they have to shelter and feed the children.
When you're not together, you shouldn't expect to also receive their income if it's 50%, regardless of who earns more. That income is not yours and 50% is half.
If you can't afford to not recieve anything and also look after the kids, you can't look after the kids and so should give responsibility over to the person who can pay.
It's not about who earns more, it's about what costs are incurred on either side for how much care they share.
If it's 50% and you can't afford a house, that is not their responsibility and you will have to let your children live with them more because you can't look possibly afford to look after them.
But you could have them for the day to see them and return them so they can go to bed in a warm house and so on.