So get upset with the BND then. That would at least have a chance of your anger actually achieving something, instead of waving your fist at the NSA from across the ocean, because frankly, they don't really care what German citizens think.
And if, because of a giant public outrage, this "cooperation" will be stopped, the NSA will not like this situation. Thus, indirectly, the NSA cares a lot, what the Germans think.
In English, the idiom "Don't care what they think" means "don't care what they feel". Though I understand how that might lead to miscomprehension from non-native speakers ;)
I do understand. My country (Australia) has US spy bases in it too ( https://en.wikipedia.org/wiki/Pine_Gap ), which they have also used to spy on Australians. In Australia's case (and I would be willing to bet that it's the same for Germany), it was a quid pro quo arrangement. Australians spy on Americans and pass the information to the NSA. Americans spy on Australians and pass it to the Australian spy agencies - thereby avoiding restrictions on domestic spying. Seriously, your problem is with the BND, not NSA, because NSA is going to spy on you regardless of whether you want them to. It's pretty much their job. You just don't want the BND actively helping them, which is why your energy should be directed towards them.
That's not all the US is doing in Deutschland. "[T]he slides show that the facilities at Ramstein perform an essential function in lethal drone strikes conducted by the CIA and the U.S. military in the Middle East, Afghanistan and Africa."[0]
So it is not just spying on the EU that is being enabled by Germany's government, it is the entirety of the US drone program that is being used across the Middle East and north Africa. This program, operating as it does outside of declared war zones, is very probably illegal under German law.