You don't have to tell anyone. By not telling him, you're protecting yourself, in your present circumstances.
Perhaps it is time to start therapy. It will take a long time and be upsetting. Tell your GP, ask for talking therapy, get on a waiting list.
You are under no moral obligation to tell your DH, at all.
I would also note that you are 'not emotionally close'. I only had one pregnancy but I was incredibly emotionally needy at that time. You really do need someone to talk to, not necessarily about the SA, just to get reassurance. Who was supportive in your previous pregnancies?
Sometimes, we hold on to things that have happened, keep them to ourselves, until we are ready to address them. It might be coming to the time when you are ready to address the abuse, in ways you weren't ready for before. Take it steady. Look after yourself, be gentle with yourself. There's no 'ought' in these situations.