I treated my late wife who died in a hospital in Germany from my own money. Is it permissible to take the money I spent on her treatment from her estate before its distribution if she was well off?

It is established in Islamic law that inheritance is distributed after settling debts and executing bequests; paying off debts takes precedence over other rights related to the estate. As long as the money you have spent on your wife's treatment was not by way of donation, it is considered a debt. And by her death, it becomes obligatory to settle the debt from her estate before its distribution and the execution of any bequests.
The ruling
Based on the above, you are legally entitled to take the money you spent on your wife's treatment from her estate before its division.

And God the Almighty knows best.