I can definitely sympathize with the depression. I've had it for about 24 years now. I am concerned about your statement expressing that the reason you've had depression for seventeen years is due to porn addiction. I am not aware of any credible mental health professional who would suggest such a thing.Granted, I'm assuming I understand your comment out of context, which is likely to be a mistake. Having said that, I don't think God is punishing you - you've had more than your share already.
You are dealing with some really challenging issues. I'm not clear on whether therapy or medication are options you are working with or not. Even if you are, sometimes it's not the best medication or therapeutic method available for you. I will soon be starting a type of therapy called Dialectical Behavior Therapy, or DBT, which is helpful in finding ways to reduce mental pain and anxiety in certain groups of people.
In my case, like you, suicide seems a reasonable answer to the ever-gnawing depression and anxiety I experience. DBT appears to be effective for people with strong suicidal ideation like you and me. I would recommend you get in touch with a mental health care specialist familiar with it and see if s/he thinks it could help. I wish you all the best.