Hi Dazebot,
I am so sorry to read your post and to know how this has affected you and the rest of your family. It is good that you have been able to find some peace but I’m sorry that this is not true of your wife.
If you think it would be helpful maybe you and, if she would like to, your wife could contact The Icarus Trust. We are a charity that supports the people around those with addictive behaviours.
We have trained and experienced counsellors who may be able to help support your wife make some sense of what has happened with your sister and find a way ahead.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
I hope that this is helpful. All the best to you.