Not sure what is right anymore

[Goldbubbles1]

I moved into a house a few months ago with my partner and his 19 year old child and my partners brother (36). I have 2 small kids whom I co parent with their father and I have them for half of the week. When my kids are here they share a bedroom.
Im getting so frustrated with a lot of things but mainly about finances. When we first moved in myself and my partner split everything 50/50 the rent, groceries etc. His brother started a job so he is now financially contributing to the house but he’s not paying a third of everything which I think would be fair but my partner says because his brother does not have kids that he should not have to pay as much as what we pay.
I am not even working full time as I am currently studying in college and I’m due to finish next year, I had to take a step back from work because it was affecting my ability to study. I am doing ok financially but it’s still quite difficult for me to balance everything. Am I being unreasonable in what I’m saying or how should finances be split?
I am also the one who does the cooking and they clean up afterwards which is great but it’s exhausting!

Why did you take your children into such a set up?

You were paying 50/50 to cover his brother before he got a job ???

Why did you do this? Utter madness.

Leave this silly set up.

What on earth were you thinking??? Put your children first and move out

This is such a strange set up. That said I don’t think he should be expected to pay 33% when you both have children in the house who will be eating the food, using the electricity, using the water etc and have their own rooms. Especially as the 19 year old is technically an adult! 25% would probably be more fair.

So there are four adults there full time, plus your two young children half the week? What does the 19-year-old pay, or does your DP pay extra to cover the costs of a young adult? They definitely use at least as much energy, food and so on as any other adult.

You definitely need to sit down and have a group discussion about the financial and domestic load, as it sounds like you are carrying more than your fair share.

You are being used.
This is not a good situation for your children.
This is not a good man.
Stop being used.

We were actually due to have a baby together but I miscarried, that’s why we moved in together and his brother was living with him at the time.

Where do you get money from to pay the bills?

I’m working part time and I receive student assistance

You should be paying a quarter, there are 4 adults...that said I would move back out...

Tell him you re not paying 50/50 anymore and if he's not comfortable with that then you'll take steps to move back out.

Move back out anyway. There's no law that says you have to live with each other.

Purely on the maths:

4 adults and 2 small kids, so count kids as 0.5 of a person each as they both eat less and are sharing a room.

The 4 adults are there all the time, and the kids are there 50% of the time. So count each adult as 4 "units" and the 2 children as 1 unit each.

Your partner pays 4/9 = roughly 44% (him & 19yo)
His brother pays 2/9 = roughly 22% (himself)
You pay 3/9 = roughly 33% (you plus 2 kids @ 50% of the time)

I'd probably do it on bedrooms. So split the cost into quarters for 4 bedrooms. Then you each pay a quarter, and you and DP split the final quarter (your room).

Don’t forget the value you bring to the home by making dinner and being exhausted, surely this needs to be counted?