Thank you so much for sharing your story. I can understand how very hard and painful it is for you to have lost your dad in this way.
It is a shame that you don’t have anyone to share your feelings with so I wonder if you would feel it useful to contact The Icarus Trust. We are a charity that supports people, like yourself , who are dealing with the impact of someone close to them who has addictive behaviours. If you get in touch, you could talk to one of our experienced people who would listen to you and may help you to make sense of what is happening and where other help might be available.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
I hope that you can get some support for yourself. Good luck.