Ok my dad works overseas and around a month ago he came over to visit. This one time we were in the car, driving, using his phone as a gps, and a message from a random chick pops up saying "are you sure you want this relationship?" (the luck). I freaked and ignored it and eventually got onto his phone within the next couple of days when he wasn't looking and found all the messages from said woman deleted. This was on whatsapp so i went onto his camera roll and found selfies from her (no nudes just a lotta cleavage). The woman looked as if she was from the country he works in so im assuming he knows her from irl. I looked onto call log and everything and found they'd been vid calling whenever the rest of us wre out. I've confronted him about it and he got visibly nervous but denied everything even tho id seen with my own eyes. The problem is i know my mum very well and i know she wouldn't do anything about it. My dad is very dominating and she is very tolerant. All it would do is upset her, but I also know I would've liked to have known in her position. Is there a point in telling her or do you think she deserves to know?