Hi there,
I'd recommend you read a good book on CSA survivors.
"Victims no longer" by Mike Lew,aimed at the survivors but i found it an invaluable read or "Allies in healing:When the paerson you love was sexually abused as a child" by Laura Davis
Quite often with CSA survivors they are "ok" and "coping" until some big life-change happens or even when they reach what can be seen as a "place of safety" such as their 1st "good" relationship and that's when the "Sh*t hits the fan" The same thing happened to us.My partner told me about his abuse before we got together,it didn't seem an issue...pretty soon it was the main issue in his life.
The answer (if there is one) is getting good support for him,getting yourself some support,and knowing that the CSA issues are his to deal with,you can be supportive,but you have to keep hold of"you" as it's too easy to allow the sh*t to take over both of your lives.
Four years down the line,my partner has learnt to deal with the cr*p as it comes along,it won't go away(same as his military cr*p) but he deals with it.
All the best
Celt