Did you have an agreement in writing? What did it say?
Did you share the repayments each month?
I assume you owned the house 50/50 if you did not have an agreement saying otherwise.
| Total | you| him
Cost of house | 290 | 145 | 145
Loss in value | 45 | 22.5 | 22.5
|||
Deposit | 50 | 10 | 40
Capital repaid | 5 | 2.5 | 2.5
Furnishing | 20 | 10 | 10
Total contribution |75 | 22.5| 52.5
So you contributed 22. 5 which amounts to exactly the same as your share of the loss in value
He owes you nothing and you owe him nothing.
Assumptions
The furniture is still worth €10k - you should really allow for wear and tear or he should give you back the furniture you bought and then you owe him €10k to get out of the deal.
You paid €10,000 in mortgage repayments each, but only €2,500 of those repayments were capital. The interest is the same as rent. So you were paying for the use of the house. You can’t expect this back.
The €2,000 in bills is the ongoing cost of living and is not an investment. It is assumed that this was your share of €4,000 in bills.