My Ex/friend With Ptsd

My ex boyfriend who is now just a friend has PTSD. He got discharged from the army for it. Went over to Iraq and everything. I love him dearly and want to be with him but he keeps telling me that he doesn't. I don't know if this is true or not because we have been dating on and off for the past year. He was the first one to say "I love you" and then he couldn't bare to lose me.
He has had a break down on me and told me a little about what happened over seas. Nothing that I could make sense of but I just sat and listened to him so he could get it out. He gets bad nightmares were he twices in his sleep and wakes up shaking. It scares me to death when he tells me this or I see it.
I just don't know what to do. Is he running away from his feelings, does he really not want me any more or is it all from his PTSD...I'm just confused on what to think or say to him. He still holds my hand, cuddles, and kisses me. I'm willing to stay with him and help him deal with the PTSD but I don't know if he wants me to. I know that he can't get his emotions straight or express them. I just need to know that I'm not alone in this because my friends and family don't understand that he can't help the things he does.