I need help

Hello! Happy Holidays! I have been having a very hard time. The other day I was looking at my boyfriend's tablet that he leaves out (does not seem too shady with it) and I was looking for pictures of us from when we first started going out. They were not there, and so i went to the DELETED PHOTOS and saw some very disturbing images (I am almost afraid to even say 😢) and I confronted him about it. He seemed genuinely shocked and disturbed just as I was. He told me he did not know how they go there, and his family's phones/tablets are all connected have been "comprised" recently, and other times in the past. He has a niece and nephew who are about 7 and 8 who have iphones who have a connected network with the other family members. He stated it must have been them, since he did WOULD NEVER do anything like that. I wanted to bring this to the attention of his mother (who pays the bills) because the content was so disturbing, that she needed to know (someone could get in trouble I would imagine). I have not yet had a chance to ask her about it today, (I intend to later tonight when I see her) but my boyfriend stated she spoke with an APPLE REP who advised the account was once again compromised!!?!?

My issue is I have never heard of a computer hacker INSERTING photos into a device. I wanted to reach out to others in the Apple community to see if this is something they have heard of, or even likely. It just does not make sense to me. I would like to trust my boyfriend, but I have only known him for a little over a year, and still getting to know him, so I am not sure if I completely trust him. If I knew those were his pictures he was looking at, I would need to break up with him.

PLEASE, does anyone have any insight into knowing if this is even possible? Or did he just get sloppy, and even though the pictures were deleted, they were not completely erased from his IPad? When I told him about it, he immediately ran to get his IPAD, and then cleared all of the pictures out in an instant. Does any one have any idea what is going on here? Is it possible there was a computer hacker that inserted DELETED pictures into an IPAD? The other theory was that it could have been the kids (who are out of control and over curious for children) who downloaded these pictures? I would like to give my boyfriend the benefit of the doubt here, but I also do not want to be in denial and put my self into a bad situation.

I know this was long, and I certainly appreciate anyone who read this and may have some wisdom or just their opinion on this. Thank you very much for your time!