I know this seems impossible but maybe someone can shed some light on how this happened.

I recently attached 5 pics to an email sent over my iPhone 5s (64gig) and when the email was received by my friend...not only did it contain the 5 pics I knowingly attached but as they scrolled down the screen my entire 3,500 pic collection of photos from over 10 years (about 4gigs) from Windows Photo Gallery was also attached. It doesn't end there...as Their entire collection of Windows Photo Gallery (from their own PC)appeared below my gallery. 

The attached Photo Gallery pics appeared on their screen as they would when you open your gallery...in a grid of small photo icons. The grid of photo icons was functional in that they would increase in size as they clicked on each photo.

*We each use Windows 7 and store pics on Windows Photo Gallery. (I also have my pics on the Google Picassa 3 photo gallery.)

*This email was sent over my iPhone (ATT) which only had about 200 pics on it and is not connected by Bluetooth to my PC...or any other way to my knowledge.

*I have charged my phone on their computer in the past but never been inside of the PC to download anything...They have charged their phone from my PC but never downloaded from it. (We do not know each others passwords to anything)

*I forwarded the same email to several other addresses but none of the forwarded emails contained any files other than the intended 5 attached photos.

*I am told the size of the attached photo collection was about 4gig.

*Apple iPhone tech people tell me that only the pics on my iPhone can be attached to an email sent by the iPhone.

I have spoken to people at Microsoft (my PC), ATT (cell phone provider), Yahoo (email) & Apple (iPhone) and none of them have even an idea of how this could have happened...several have said it's impossible...yet it happened.

PLEASE...Can anyone shed ANY light on this and how it could have happened? I am being accused of hacking or secretly downloading my friends Photo Gallery content and it has caused problems for me. 

Thanks in advanced for any suggestions!!!