Ok. No need for long drawn out prose here. There's only one reasonable bit of advice for you and it is this.
Before you marry this woman (or even waste another day of your limited sexual years with her), decide if your love for her and all the other things you value about her are worth enough for you to be willing to go through the rest of your life without sex if you do.
Because that is exactly what you are going to do if you stay with her. Don't try to convince yourself otherwise, because if you do you will only be in denial and will only be setting yourself up for a very rude awakening.
I repeat: IS SHE WORTH ABANDONING ALL HOPE OF A FULFILLING SEX LIFE FOR? If you can absolutely and unequivocally answer that question yes, then write out the check for a lifetime supply of masturbation lube and kleenex and go for it. But if you have even the SLIGHTEST hesitation, RUN, get out while the getting's good, and don't look back.
