I do not know the law in Minnesota. In my opinion it really doesn’t matter what “the law” is.
My guideline is this: One may use deadly force whenever the threat one is facing makes one TRULY fear for one’s life or the lives of those whose protection is one’s responsibility (e.g. family and invited guests on one’s property).
I live in Virginia. We do not have a specific “Castle Doctrine” law in place to protect us from improper prosecution in self-defense cases. However, I will continue to use the above guideline regardless.
As the old “cliche” says: It is better to be judged by twelve than carried by six.
Just because it is an old cliche doesn’t mean it is NOT true.
Check with a lawyer, Apply for a concealed handgun permit, find a comfortable handgun, and take a self defense course at a local range with a certified instructor.