Surgery or radiotherapy?

Hi everyone I desperately need your help and advice. I was diagnosed with prostate cancer two months ago  My PSA was 18, initial MRI scan showed that the cancer was contained within the prostate and biopsy showed I had a Gleason 3+4. Since then I have had an isotope bone and CT scan which I have just been informed confirmed the cancer for now had not metastasised. The recommendation was that I have surgery, via robotic radical prostatectomy but the side effects of abdominal scarring (five insistions), bladder incontinence (possibly temporary), erectile dysfunction (again possibly temporary) reduction in penile length and dry orgasms really concerns me. I was told (and read online) that although radiotherapy (both the external and internal treatment) will naturally circumvent the scarring and reduction in penile length, there would still be dry orgasms and the long term (3 months to 2 years) bladder incontinence and erectile dysfunction could be more severe or permanent. I am 57 with no children. I was told (or it was suggested) that just surviving this disease should be my priority but the reason I’m struggling to make a decision is I am beginning to feel the quality of that survival is if not just as important…perhaps more.

I guess my question is, does anyone have any advice as to how to choose between the two options. Have you had radiotherapy and have any advice as to what to insist upon to minimise the late effects of bladder incontinence and erectile dysfunction.

I am wary that every moment I delay making a decision gives the disease opportunity to spread.  Please help if you can and thank you for reading this far.