How do I modify final divorce decree regarding community property?

You need a deed of trust to secure assumption. This will allow you to continue making payments on the mortgage and free your ex wife from having to do so.  Under an assumption deed, the grantee becomes obligated to the grantor – but, it should be pointed out, not to the lender, since the grantee has not signed the note. Similarly, the grantor has not been released from the lender´s note, unless the lender has approved the assumption and expressly released the grantor in writing. An assumption deed is usually accompanied by a deed of trust to secure assumption, which enables the grantor to make payments to the lender if he discovers that the grantee has failed to do so, and then recover these "advancements" from the grantee. This enables the grantor to proactively preserve his credit. If he is not reimbursed by the grantee, the grantor may foreclose.