I'm was a bit older than you when I was diagnosed with Gleason 3+4 restricted to one lesion. I took a very different path, electing for focal therapy in hopes of minimizing negative impacts on sexual function and urinary continence.
I had cryoabaltion of the lesion almost 2 years ago and I'm happy with the outcome. My sexual and urological function are unchanged. My procedure did not have to include any nerves due to my specific presentation.
I opted to accept high(er) recurrence risk along with likely minimal side effects. For me and my age, I wanted to kick the can down the road and if I have a recurrence, see what medicine has to offer years from now.
Taking your time, talking to lots of guys similar to you, and seeing if you have unusual options that might fit your situation and treatment goals are good uses of your time I think. In the support group I attend guys are pretty surprised at how optimistic doctors are about sexual outcomes vs their own results. Of course, guys in support groups are probably much less likely to have had optimal results. I'm guessing those guys don't feel the need for a support group.
Also, enlist your support system to help you sift through all the data and talk about it and how you're feeling. Unless you can find otherwise, remember most of the published data on sex is about *vaginal* penetration, not anal.
Breathe, read, talk, breathe some more, then decide. Very best of luck!