I still owe you an answer.
The whole thing turned out "well" for me.
In the end, she went to a lawyer and demanded 50,000, for the house, money she had lent me, and jointly purchased items. Actually fair, although originally she wanted less, but over time she thought of more. I have to admit, probably my own fault because I let too much time pass before I took care of it.
Financing through my bank was not possible because they would not have revalued the house and therefore could not cover the capital requirement.
I was then in contact with several financial brokers. In the end, HVB made me a great offer to
a) redeem my old loans at BW-Bank including prepayment penalty
b) the 50,000 for the ex
c) notary and property transfer tax.
Term 20 years - at 2.04% - full repayment.
If you still have questions, bring them on.