köpa ut mitt ex

Hej, jag skriver eftersom jag har en fråga. Jag kan svenska, men är lättare för mig att förklara mig själv på engelska (men du kan svara på svenska utan problem) :)

Im writing because 2 years ago I bought an apartment with my, now, ex sambo (50/50). I would like to buy his part of the loan so I can be the 100% owner of the apartment. The only problem is I don't know how much money should I give him, because all the questions I have been looking has always an increase of 22% in the value, but this is not my case. So can you please help me? We bought the apartment for 2.350.000. The bank gave us 2.000.000kr for a loan, and the rest was kontantinsats (his father gave us 250.000kr and his friend 100.000 -the friends money is already paid-). We tried to sell the apartment 3 times for exactly the same price as we bought or even less, and nobody came to the visning. The mäklare told us that now the apartment has not increased value. We have paid a little bit from the mortgage we asked to the bank, so right now the debt with Swedbank is in 1.914.000kr. How much exactly should I gave him? Because I want to buy just his loan, not again my apartment for a high amount, because I already bought it 2 years ago. It is only that. I just want to know the price I need to give him.

Tusen tack för allt
Mvh