I'm a teacher and the student know my address. What should I do.?

I'm secondary school teacher and teach geography to mainly y7(12-13 years olds). Recently we have been doing a project of house prices in different areas and groups of students went and took pictures of different things each area had. One group didn't have a camera so I let them borrow my iPhone to use the camera, something I regret. Not thinking about the time the amount of information my phone holds, like address, my wife and my son pictures ect. Later that week a few students were calling me by my first name, instead "sir", or Mr dell, but didn't think much of it. This was kinda all through the year 7 groups, so it must have been rumoured around. Than a student said to me, "your sons got really blonde hair", which made really suspicious. Than later that week a bunch of students turned up at my doorstep, and asked if they could have a drink. I gave them two cans of coke to try and get rid of them, and asked how them how they knew where I lived and they said "everyone does", which worried me. I asked the group that used my phone about it, and they said they let this group use it, meaning it had been through the hands of 45 student. They even know my son name and school he goes to. I'm the head geography so it is really un professional to have the students knowing this information. I live about 20 minute drive away from school, so than they cant find my house. What should I do. I'd rather not tell the subject head, because it does state in the rules not to lend any student a digital devise which contains your information. What should I do. Should I just let it p.