Hi. I don't have a referral for the San Antonio area, sorry. Maybe Cory will stop by and have some idea. Meanwhile, you could check your phonebook for possible leads and call to inquire if they have any experience with hoarding and/or check online. Do you think she may have OCD? You can check under that because sometimes OCD specialists also cover hoarding.
But, since you don't think she'll be willing to go, perhaps you can approach it as a desire to go to family counseling (include kid if you have any) and ask her to go with you. It is normal for families of hoarders to need some help, too, and going as a family can help make it not so "blaming" against her.
Be careful not to blame her. She cannot help it and it isn't being lazy. Ask any questions you like, and go ahead and read up on this website. Best of luck.