So sorry to read that you are going through this.
Try to handle things one step at a time.
He is using, you kicked him out...ok the biggest problem has been handled for the time being.
Now what to do about the insurance company...
What did he say happened? If it is an at fault you would have a deductable even if he gave a statement. If so, it wouldn't matter what the statement says, so no statement is truly needed.
If it isn't an at fault... just tell them what you know and tell them he is out of the house for personal reasons and you have no way of contacting him...your statement is all you can give them. They accept that or you have a deductable.
So a deductable is the most you need be concerned about on that matter.
As for missing money and the necklace... if he took them, there is only a slim chance you will ever see either of them again. Take the loss and move on or put in a police report and maybe never see them anyway but still you will need move on past this storm either way.
Your not alone.
You have us here at SR and you have family. Gather in the support that is around you and together, not alone...you will get past this.