About 25 yrs ago I was in the same situation; only the numbers were different. I also opted to stay in the house and I needed to re-mortgage as well. I paid the whole cost of the new mortgage myself. No need to get into a fight over a relatively low amount of money.
In the other case, she and you will equally 'benefit' from the sale minus the 7,000 fee. I think that those costs should be 50/50'd as well. I cannot see how she or her lawyer will agree with her paying the full 7k fee.
Keeping things simple will be better in the long term. No need to 'waking a sleeping dog' as they say in Dutch. Being on a watch-related forum, I guess that you have a collection yourself. (Under Dutch law) she could argue that those watches were bought with household money and that the sale of those watches should benefit her 50/50 as well... That's how a friend lost his classic Alfa Romeo... He had to auction off the car and he had to hand over 50%.
Menno