How to talk to a guy about his private issue?

My friend (guy) told me in an email he got his 4skin torn from heavy friction whilst we were humping, I have no idea what to say that will make the guy feel better, I'm still shocked it happened I didn't know it could happen :( possible scarring... I'm so worried about saying the wrong thing :( I don't want to make him feel bad about it.. and I know it will heal eventually, but I want to reassure him, I want to comfort him, give my love and support and express my regret we were a bit too rough :/ oh man... he trusted me alot to tell me about it, and I don't know how to respond when I see him tomorrow...I'm still stunned :(