Help with failing marriage as a result my low sex drive

[Ravenr]

Hi
Out of my history of porn addiction and probable narcissistic traits, you may understand why my marriage of 26 years is in dire straits. I have a too low sex drive, which is probably all in my mind. Some very few times I have managed, with God's help, to have sex with my wife without sex fantasies going on in my head. I am done with those as they have a huge negative effect on my faith, but how do I take back control of my mind and my body? How do I pursue my wife sexually? How do I get aroused by her and not fantasies?
Truly need help please