I've been there, a strange feeling isn't it. You can always ask for it to be removed if your quick enough you might and I say might just be in time to get it removed before someone copies it and reposts. Of course, by making this post you have only drawn more attention to it and the chances of it being spread further, Whoops.
I was posted in fifty different places but luckily it has reduced to six that I know of when tumblr went prudish. Now I've had that lucky break I will be more careful with my photos but it is probably too late for that. I might not reach that level of exposure again but who knows as you have found out it is no longer in your control and will never be again.