i think that you should hint or tell your dad that you know what's going on, and how you feel, and how your mom would feel if she found out. If he's a good dad, then he'll stop and listen to you and try to stay loyal to you and your mom. If he doesn't, maybe he is a fucking pig.(sorry!)

~ MaRcY!

Tell your Dad. He needs to know its not a secret anymore. You need to tell him how you feel and how your mom would feel if she found out. You need to scare him for sure.