I'd really like to know from a guys perspective

So about a month ago I found masturbation videos in my fiance's phone trash (he doesn't know they don't perm delete) they were from a month or so before I found them about 4 and they were whole he had me out running errands for him from the time and date, I also found a pic of a girl, I know he was lying why she was on there but never found out why, he locked his phone for a month and wouldn't let me see it at all when I'd ask. I was so upset he had me locked out bc of what I've found in the past also, I've found him on dating sites( yes I'm stupid for staying we have young kids) well he took the lock off and forgot his phone or purposely left it so I couldn't get ahold of him I'm not sure I found it when I made the bed well obviously I looked bc since he locked it he's been up late getting texts and snap chats and also while he's in the bathroom I didn't find any messages he can delete those and they are gone forever but I looked in the trash and I found some other girls Snapchat picture and a add me on it then I also found 8 yes 8 masturbation videos? Is there any other reason to have these and delete them they've never once been sent to me. Am I overthinking this or am I right about what I have been fearing this whole time?