27, Only found this and any advice would be great!

Hi guys, 27 year old male here, and only discovered about PIED now! Ive been watching porn from the age of about 15 up until now and always wondered why I had problems getting an erection. I had a girlfriend for 5 years in between that time and always had great sex but ever every now and then it wouldn't do its thing to the full 100% like It should. I was still watching porn while with her aswell. After we broke up I had chances with girls and failed miserably. The other week I had the most gorgeous girl in my bed and I just couldn't do anything at all like nothing was there downstairs at all. I feel so shit about myself and I never knew what was wrong with me. So ive done a lot of research and im now on day 3 of no PMO but what should I do from here? How long should I go for and should I not masterbate at all either? Some info with people that have been cured would be great as im feeling pretty down about the whole thing at the moment and I really don't know what to do. Thanks guys.
And may I add the way im feeling at the moment I don't ever want to watch porn again and it makes me sick even thinking about it after what its done to me!!!!!!!!!