my opinion might differ slightly, but here goes.
As a parent, your first duty/responsibility is to your children.
I understand your wanting to "help" him make this journey, however if your 11 yr old is aware and concerned that should be a flag for you to acknowledge. Make sure her world is as safe as you wish his could be. Its so hard watching someone you love be in this much pain and unfortunately, it will get worse before it ever gets better. Now is a great time (if you haven't before) to have a family meeting and advise, (age appropriate , of course) on what is occurring. It is also time to set boundaries of what you will and will not accept in the household. This will set an example for your daughter that she will take with her always. Children learn from watching how adults handle situations in life. What message do you want her to take into her future relationships???
either way you are in for a ride....i wish you peace in whatever you decide.
"Insanity is doing the same thing over and over, and expecting different results."
I cannot take your steps, but I can walk beside you, if you'll let me.