1) Forget about H. Seriously. File for divorce if it benefits you financially, stay as you are if it benefits you. (If you're getting close to 10 years married, wait until after 10 years if you can - gives you the option to collect on his social security benefits later if you want.)
2) Focus on SD. You are now the closest thing this girl has to a mother and she NEEDS you. See if you can get H to agree to a visitation schedule. Take as much time with her as you can get. She's vulnerable and at risk. And read him the riot act about leaving a 13 year old girl all alone overnight. I know you probably don't have a legal right to visitation (but check with a lawyer) but he may well let you step up to the plate anyway if he's that selfish right now.
