@Hilfemich
Yes some live abroad and it’s a third world country, people disappear there to escape criminal charges here or if they’ve been taken back home to marry. I don’t think he’d do that BUT it does happen.
When we're in the clutches of an abusive man our 'denial' tells us "Oh, he would never <insert behaviour>". And then he does.
Remember, right now you are in uncharted territory. You don't know what he might do. At this point I'm sure he thinks he has you buffaloed and you'll be back in your box soon. But his moment of realization will come and at that point all bets will be off.
Again, I'm not trying to 'scaremonger'. I'm just concerned that you are downplaying this particular danger (and possibly others). All the while 'up-playing' other fears (ie losing the DC to him). Doing this will 'paralyze' you and prevent you moving forward. I guess my point is that you do need to consider ALL possibilities, whilst trying to keep calm and quietly make your own plans. So, as far as this particular danger, if you know where the DC passports and birth certificates are and you can quietly move them out of the house, do so. Then deny knowing where they are if need be. At the very least, take pictures of them so you'll have the information you need to alert the passport office and/or get new ones.
And PLEASE see a solicitor. And let your family and friends know what is going on and that you want out. Now is not the time to be embarrassed. Now is the time to say "This is what I'm dealing with. Help me".
Another thing, if you are not in touch with friends and family, ask yourself why. Has he alienated you from them or vice versa? Has he engineered quarrels and then demanded you take 'his side'? Has he bad mouthed them to you and made you feel they "don't really like you?". Are you embarrassed or afraid to contact them because of this? If so, I guarantee that they miss you and have been praying for your call. Yes, you may have to hear a few chorusus of "We told you so", but in the end it will be so worth it!