It must be a culture shock, I can see how you must be feeling really strange. Are there support workers? If so, try telling them how you feel, maybe they can introduce you to others? How about the social workers assigned to you, you could tell them how you feel and ask for suggestions and support. I think reaching out to others in the refuge is the best thing you can do right now. The people you are around will have shared experience with you, they will understand a lot of where you are coming from. I know you've been terribly brave and it can be a strain to keep it up, but reach out to others who seem nice if you can summon the strength. And you don't have to talk about the heavy stuff, just chit chat about the kids and the weather is fine and will be welcomed too I expect. Openers like "How old is he/she?", "Grotty/lovely weather isn't it?" are a good neutral way to begin.
Try and be patient with the other kids, they've all been through a lot and will likely have some behavioural issues from the abuse they suffered. Not fun to be around, I know, but it's not forever. Grit your teeth and smile graciously around the little beggars 
If you're at a loose end, perhaps take the kids out for a walk during the day? A visit to the local library, get yourself and the kids some books to read? Coffee shop for a nice treat? A visit to the park? Local toddler group? Museums? If you check out mumsnet local for your area there will be lots of suggestions for things to do with the kids to fill your days. In libraries there'll likely be a free magazine for families with listings of stuff to do in your area.
Have you contacted any friends or family to tell them what's happened, or is that still a bit unsafe right now?
Also, we're always here for support if you need it, keep posting if you want, OK?
I think at the moment it's best if you try and focus on yourself and the kids. It must be second nature to always be thinking about him before anyone else, but he's not your responsibility, he is a grown up and if he can't cope without you then it's about time he learned.
Also suggest you visit your GP and tell him/her what's happening. They might be able to refer you for counselling to cope with all of this, or drugs if you want them. You're doubtless in shock right now, so just cut yourself a break for a bit, take it easy and try to care for yourself for once.