For him, this is something that happened 13 years ago.
For you, it happened last week.
He thinks he's put it all behind him.
You are suffering in this moment.
Take time to deal with this. I'm a fan of IC (Individual Counseling) for dealing with this. Don't make any big decisions until you have had some time to settle down.
It will likely take you months, maybe several months, to deal with this trauma.
Read a lot in the Healing Library. There's a link in the yellow box at the upper left of your screen.
If he really means "He said he did not say anything for 13 years because he wanted to spare me the pain and he feels that he loves me more than ever before because of this.", then he needs to step up and do what it takes to help you heal. He needs to take responsibility for what he did, and for helping you get through this.
ETA: (Edited To Add) There's a thread in the I Can Relate forum for those who found out years later. It might be helpful to see others who share your experience.
[This message edited by TrustedHer at 8:16 AM, June 4th (Wednesday)]