As much as I know he hasn´t written a public letter, but has given an interview to the web-magazine yosthlm.com.
http://www.aftonbladet.se/vss/nyheter/story/0,2789,79699,00.html
This interview was a reaction on reports in Svensk dam Tidning, saying that he has betrayed Victoria with an other girl (I think her name was Linda something).
He said among other things about Victoria:
– Vi har tagit en välbehövlig paus från varandra, men vi har en väldigt stark relation och nära kontakt, säger han.
– Tidningarna skriver ofta osanningar om mig, men i det här fallet skadar det inte bara mig, utan även den person jag haft ett riktigt förhållande med.
-We have taken a necessary break from each other, but we have a really strong relationship
-Newspapers write often untrue things about me, but in this case this doesn´t only harm me, but also the person to which I have a real relationship.