Searching for an old favourite

[Telemmaite]

A fairly long time ago I read a story about a son who finds pictures of his dad getting fucked with a strapon by his mom. The story leads on with the son going on a trip with his parents (to a family event I think) I never got much past that, and I haven't been able to find it back since.

Oh, when the son is experimenting with anal I think he uses a roll of lifesavers.

Help finding it back would be greatly appreciated,

Thanks.