if it was me ild be letting him know that you are there for him and that you are prepared to listen to him as much or as little as he wants. If you can try and borrow the book Victims No longer from the library that way youre not wasting money if he is not interested in reading the book but its the male version of The Courage To Heal. Maybe even let him know that you belong to this group and that there is a group specifically just for guys on here as well. . if he is interested let me know and ill provide you with the details. Guys really arent great at talking about this stuff as I am sure you know but just let him know you are there and that just because he has told you this it isnt going to change the way you feel about him.

thank you. and kris is more like the keep it sll inside kind

I would encourage him to talk about it with professionals paid or school councelor. It is great that he opened up to you. That is the first step. This is also more than a girlfriend can handle on their own. Telling a trustd person and working on it in counceling are two different things. My boyfriend had no clue what to do with me when I was having flashbacks and night terrors and other crazy making behaviors he had no way of handling.

He told you because he wants to talk about it...it's possible he hasn't talked about it because of shame. He may need reassurance it's safe and he won't be judged. He may have been testing the waters to see your reaction.
IMO the last thing you want to do is act as if you never hear it ...just leaving him alone. That's likely to be seen as meaning it isn't safe. It's possible he doesn't really want to talk about it because of how uncomfortable it makes it. So you you can't push him too much but do need to encourage him. Tell him your sorry for what happened and sad for whatever it was that caused him to feel he needed to hide it as you want him to feel safe to share anything. Let him know you know he must have a lot of feelings about what happened and that you care and will listen without judgment whenever he wants to share and encourage him to do so. As Tyzz says to share as little or as much as he's comfortable with....just know it's a big deal... anyone being raped by anyone at 10 is a big deal.
He's your boyfriend, these very personal and painful things are important....trust is so important. How can either of you achieve intimacy if you don't feel safe enough to talk about events that happened that so profoundly shaped your lives and affect your relationship? Trust is the foundation to all relationships...love relationships should be the safest ones of all to talk about things that make you, you. So by all means bring it up..let him know it's safe to talk about anything with you. While you can listen, if it's something that he's clearly very troubled by still, encourage him to pursue couseling. All you can do is be a supportive ear.