From this very good article a Google translation which describes the according German law which your ex-boyfriend violates:
In most cases, however, corresponding photos are taken with the consent of the person depicted or even made by the person himself and then sent or handed over. In these cases, §§ 33, 22 KunstUrhG protect against unauthorized distribution of these images.
In these cases, however, it does not matter whether the photos are intimate or not. The dissemination of portraits of other people without their consent is generally prohibited by § 22 KunstUrhG. Failure to comply may result in imprisonment of up to one year or a fine in accordance with Section 33 of the KunstUrhG.
Here the link to the law §§ 33, 22 KunstUrhG and here what happens if you violate this law. Both links are in German but I assume your ex-boyfriend understands German? (you can do a Google-translation as well).
Probably your ex-boyfriend is not aware of this. Since you know his name and you can probably contact him, let him know that he violates this German law and that you are going to inform the police immediately if a picture of you pops up anywhere. If this is clearly communicated by you, it might solve your problem before pics are sent around.
Depending on the content of the pictures and your age, your ex-boyfriend might also violate the German "youth pornography law", see here and do a Google translation in case you don't speak German.