I am 50% Eigentuemer, land register, my ex-boy friend took

Datei angehängt (G21TT43)

Hi Alva, thx, here is chronologically background:
1. From 2019, we bought the house together and planed to live inside, he voluntarily took the loan part. then he got a job opportunity to move to Switzerland and from then on we lost the contact.
2. From 2020 we started notary draft and bank loan transfer application, that he sells me his 50% property right, 250k as 50% of market price on notary draft, during i have been still preparing from bank, he was not satisfied the price, and now he terminated the contract draft and requesting half loan part from me now. I assume after this case, he would consider sell the 50% his part.
3. i have plan since 2019 to move in with my son and to have school in that new city. because covid and his school offer from middle school, we decided the changing/moving point is next year.
4. i tried contact him last year to ask if we r already separated and attempted several time to pay him half rent, but he did not give bank IBAN, so i think rental part is not in contradiction. once i move in next year, there will have no rental receiving from other tenant, because i will be sole tenant and half owner.waiting for you advice and help, thanks a lot

Hi Alva, i have one more question that i forgot to ask earlier, regarding the gift attribute of this 50% ownership i have. if it's not a gift, i can not keep it, which means eventually i need pay half debt?