Ask for these restrictions to be given to you in writing.

I agree with the other commenter, that you should have kept your private matters on a "need to know basis", but that is a moot point NOW. You are confronted with this issue and you will have to deal with it.

Define what it is you want to achieve. Then work towards it, using all means that are available to you. It is probably not legal to deny you access to what you call "the public terrace of the house", so a threat to take legal action will most likely make her back off. (I don't know anything of German law in such issues though.)