My familys not Nazi... but were mostly German and being Geman is awesome! My brother was even born there. Germany is a very interesting place, you should do some research on it to learn about your heritage.
Now was your grandfather a nazi or was he just a soldier fighting for Germany because many don't know this but a lot of German soldiers fought for the nazi government but actually were not affiliated with the party and some had no knowledge of what was being done to the Jews others did but were either higher ranked or actually served in a camp which would have made them SS officers thus a nazi. it's just like how many American soldiers served or serve and fight even though they might not have agreed or do not agree with the war they are serving in, the same went with the German soldier during WW2 many soldiers only fought to serve their country and might have not agreed with their government.