TURP Effects on ED?

I have BPH and had surgery for it (TURP) about six years ago.  I had never before been impotent, never.  After the TURP operation all sexual feeling died away.  I sometimes wake up in the morning with an erection, but I can't turn that erection to any sexual use.  There's no feeling left in my penis.  Luckily, my wife of 40 years never was keen on sex, so I don't get any complaints.  The doctor who did it says it's all in my head!  I very much disagree.  I tried Viagra once.  To no effect.  Any constructive input would be appreciated.

Thanks in advance,

Jaffer444