This is really hard for you but there are people who can help. I work for a charity called The Icarus Trust. We try to support people like yourself who are dealing with addiction in their family because we know how difficult that is. We offer a free service and if you contact us we would put you in touch with one of our trained volunteers called ‘Family Friends’. These have lots of experience of talking with people like yourself, would understand what you are going through and, hopefully, help you to see a way ahead and what other help might be available to you and your family.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
I really hope that you are able to get some help for yourself and your dad. Good luck!