Here's what Ramsay wrote Jon, in full:
To the traitor and bastard Jon Snow,
You allowed thousands of Wildlings to pass the Wall. You have betrayed your own kind. You have betrayed the North. Winterfell is mine, bastard. Come and see.
Your brother Rickon is in my dungeon. His direwolf's skin is on my floor. Come and see.
I want my bride back. Send her to me, bastard, and I will not trouble you or your Wildling lovers. Keep her from me, and I will ride north and slaughter every Wildling man, woman, and babe living under your protection. You will watch as I skin them living. You will watch as my soldiers take turns raping your sister. You will watch as my dogs devour your wild little brother. Then I will spoon your eyes from their sockets and let my dogs do the rest. Come and see.