I'm very sorry for what you are going through. As others have said, please protect yourself and do what is necessary to allow your son to face the consequences of his actions.
I feel for you, I really do. Please know that you are not alone. As Ann said above, this is a common occurrence. My x stole checks from his employer, just about 5k before he was caught. I, too, was robbed of money, jewelry, etc. I simply cannot wrap my head around why addicts do what they do, without thought, but I know it's just "what they do" when they are sick in active addition. There's even studies shown that certain drugs essentially "turn off" the rational, moral part of the brain. I'm not sticking up for an addict, by an means, I'm just saying it is NOT personal. They aren't doing these horrible things TO US to get back at us...the truth is they probably aren't thinking about anything at all, other than getting the means to get high.
I'm not sure if you are in Alanon or Naranon, but if not, I encourage you to look into it for support from others that can relate. I just started reading the Alanon "big book" and the back of the book is full of stories on the heartache addiction brings and how to cope.
Hugs to you. Please know we are here for support!