You're asking the questions so many others have unfortunately had to ask, it's sad that you have to.
But your partners just done the hardest thing he'll ever be likely to do, he's broken the secret and told you.
It might not seem like it but he's probably overcome with relief - and confusion.
The roller coaster starts here.
Try to get him to see a good therapist, ask what experience they have with abuse victims and survivors. It's important that they know how to deal with our particular problems, because we've got them !!
Most of us have tried the do it ourself approach and it's not a great success, although it's what's got us to the stage when we realised we needed proper help.
Read what's on this site, there's some great stuff on the friends and family forum, and some good partners there for support.
You're both going to need it.
There's some excellent books on the recovery process, my particular favourite is Mike Lew's Victims No Longer, a remarkable book with good advice for both of you. It's available through Amazon for about $20, worth every cent.
Look on the books forum, and the home page, for other good stuff.
And as for what kind of support to give ? we need lots, sorry but we do. Knowing that someone is there helping us along, someone still cares and hasn't rejected us for what was done to us, and cares enough to want to see a survivor at their side instead of the empty shell we are as victims, that's the kind of support we need.
It's tough going, and if anyone tells you it's easy don't believe it. So take care of yourself as well, you can't recover for him. But he can with you.
Go confidently in the direction of your dreams! Live the life you've imagined. As you simplify your life, the laws of the universe will be simpler.
Henry David Thoreau