Can everyone see my photos on iCloud?

My whole family has iPhone 5's and my brother set up iCloud on my phone. Well I forgot about it and today I sent naked pictures to my boyfriend (No, he didn't pressure me, I wanted too). After I took the picture I realized that everyone on iCloud might be able to see it cause it's in the photo stream thing and I can see some pictures that him and my sister have taken on their phones before. Does that mean they could see my picture!

You would have to message this applications customer service directly as these applications are not directly managed by Facebook