Did Jacqueline plant Phillip's cufflink or did she sleep with him?

[Arlene Halloran]

I can't remember. It is a while since I've watched season 3. Jacqueline's so called gift from the grave to Angela was a key to a hotel room and in that room was one of Phillip's cufflinks, with a note saying she had slept with him. Was it real or a lie? Maybe Phillip lost his possession and she stole it.

 

[Snarky Oracle!]

Well, he sure seemed to get nervous.

He was either guilty, or the whole idea of it gave him the heebie-jeebies.