How do i get rid of sins in islam form watching pornographery and mastubrating?

im 14 and i was ADDICTED TO WATCHING PORN AND MASTUBRATED but today i dient mastubrate but i watched porn and i feel like im going to die because i promised to allah swt like 60 times and failed to keep it, but right now i promised and im keeping my promise becuase i know im done. BUT HOW do i get rid of this guilt, it makes me feel like im going to die but every thursday im going to the mosque to pray mugrab and isha and the sayaad prays this dua that gets rid of thousands of ur sins BUT PLEASE ANY TIPS ON GETTING RID OF THE GUILT PLEASE HELP NOTHINGS WORKING