Girls need some advise!

So was on my boyfriends phone yestirday and noticed he had old msgs from his ex who he was with four five years, the msgs were from before we were together but attached the msgs were his ex’s nudes and videos, they weren’t on his images app and this is a new phone so unsure why her msgs are in here anyway he’s saying he thought he deleted them ages ago. I can’t help but feel mugged off there’s no need for this to of been on his phone it brings up the issue of did he keep these to look at ect ...

there deleted now but it’s a bit to late they were still on there it’s caused a issue and I feel deflated by the situation it’s ruined Valentine’s Day

I just want some advise on what others would do on this situation it isn’t the first time things relating to his ex has caused problems with us and now I’m questioning if this is a gonna be a common thing if it’s worth carrying on there’s on so much a girl can take