I am a firm believer that sex after prostate cancer is what you make of it. My husband has had radical surgery, pelvic radiation and years and years of hormonal manipulations, chemotheray and radiation to bone mets but he still very much enjoys having intercourse and orgasm.
He did opt for a penile implant about three years into his diagnosis. This has been one of the best things that has happened to us since his diagnosis. With the implant he does not feel impotent and as a result he continues to enjoy the sensations of orgasm even though the hormone therapy has impacted his libido.
He believes that the most important sex organ is between your ears and that if one has the right mind set they can overcome all of the obstacles that would impeded sexual function. His focus has always been on bringing me pleasure and in the process he always becomes aroused and reaches orgasm.
I'd suggest treating the erectile dysfunction with one of the various treatments available and then focus on bringing pleasure to your partner and not on yourself. In the process of watching your partner respond, you will be surprised at what you might feel emotionally and physically