Hi Poppy,
That is a very difficult situation, but it is one you may need to discover the answer on your own. The Icarus Trust provide Family Friends for you to speak to, who has been affected my addictions too – so they can relate to similar situations. Often speaking to someone and letting it all out is the best way for you to discover what it is your should do. You can contact them on info@icarustrust.org or go to their website http://www.icarustrust.org.
Best of luck!