1; How did your partner tell you of his CSA?
I found out that he had been cheating on me. Confronted with his transgressions and the real possibility of me leaving I think he felt forced to tell me.

2; Did you suspect there was something wrong?
Very much. First I suspected something, then discovered the cheating. However that took place early in our relationship when we were head over heels in love. So the cheating somehow didn't make sense to me. Then anything he told me about it didn't make sense (you know the picking-up-men-from-craigslist-story).
Whatever he told me, however he appoligized and however he tried to make it look like he was just had a big sexual appetite there was a gut feeling that there was more to it.

3; Did he immediately start a program of recovery?
No. He keeps finding reasons to postpone, the new job, the big project, the summer vacation, etc. etc. But he started reading some books about it and is slowly, slowly opening up to the idea of therapy.