ANSWER:
MASTURBATION AND ADDICTION TO PORN
This feeling of guilt will soon fade away as your heart will get accustomed to this filthy Sin which would subsequently lead to the death of your heart. If you don’t put an end to it, it will lead to more serious things that can be beyond repair such as impotency! Fear Allah and stop it NOW.
Get married if you can, otherwise fast every alternate day and always lower your gaze.
Cut all means that lead to such a sin, like cutting off internet from all devices, stop being alone and always occupy yourself with something constructive and keep your mouth moist with the remembrance of Allah. Keep good company, surround yourself with practicing brothers all the time.