Camera in my boys bathroom

Today was a really bad day and it's been filled with a lot of emotions. My boyfriend picked my son's up from their grandfather's house today. He's their dad's father. They still hadn't packed. They're 13 and 15. They have their own room that they share at their granddads house because they're over there every week. I've picked them up several times. I've also been in their bathroom and never noticed anything weird. The shower doesn't have a shower curtain but their granddad said he kept forgetting to get one but it's okay because the door locks. My boyfriend went to help them pack because he was in a hurry and he went in their bathroom to use it. The bathroom is connected to their room. My boyfriend is autistic and he has always said some people with autism have special talents. His is his sight and ability to notice things nobody does. So he noticed the wall outlet that faced the shower has something strange. He went to look into one of the holes and then used his phone flashlight. Their granddad was outside so he asked one of my sons to get a screw driver for him while their granddad was doing things outside and took the outlet off the wall and held his phone flashlight and noticed their was a lense in that outlet. After that all hell broke loose. My ex is convinced there is a misunderstanding and his dad isn't a creep. What could the misunderstanding be. I really need someone to tell me scenario that would make this not awful because I feel like I gave my children to a predator and never knew.

Edit: Sorry! We DID call the police. Which is why my kids dad is saying there has to be a misunderstanding and is defending his dad.