I think my dad's having an affair...?

You should talk flying dad about it say, " dad when I was playing games on hut phone the other day a message came in from ___ I didn't open it, but it sounded a little too friendly. Who is she? And does mom know about her" if he pushes you off tell him if you don't get answers you're going to talk to your mom. Affairs are a serious thing. And if his 14 year old daughter knows, he's taking it a little too far. Best of luck Hun!