My social psychology teacher once told my class that the "optimal" age for a female is 20-23. He wasn't trying to be sexist or anything, but in terms of fertility, peak physical condition and all of the other aspects that are hardwired into a male's brain, girls in that age group will always be the most "attractive". He had a fellow psychologist that took all of this one step further though. When his friend was 20, he dated 20 year old girls. When his friend was 30, he dated 20 year old girls. When his friend was 40, he dated 20 year old girls. And now his friend is over 60, and he is still dating 20 year old girls.
You're definitely in a tough spot and from the sounds of it, this will just continue to eat you up even after it has been resolved. The question is... are you willing to lose a friend?