That's really good news Steph
Yes there is a lot to get through now but the road ahead is a little less rocky for you both. You will always have the so-called "squeaky bum" affect at each PSA result over the next years, after treatment, as we all do and that will remind you of this experience and won't be pleasant. We all get it, cure or no cure as the results are usually meaningful in terms of successful treatment or a change to a new treatment or none at all.
I know what you mean about grief, I had the same type of experience when John was diagnosed, I felt intense grief for the loss of my husband, our intimate life, for my children (adults, but it's your dad right?) and our shared future and yet four years on he is still here, against all the odds. If someone had told me that at the time that we would have four years or more I would have jumped up and down and kissed them!
It does look like you will not have to know the reality of those feelings for a good time yet and with luck, your other half will live a normal lifespan. You may even find that your life together is enhanced in many ways as the realisation of what might have been dawns for you both. I mentioned before (I think) that despite my own husband's bleak future the last four years have been bliss from the point of view of love and partnership. We do strongly recognise our love for each other and despite the illness, we are grateful for that at least.
Time to now think carefully about your options, read, take advice and make the most of the time before the operation or RT, have a holiday if possible, get close and personal with each other and enjoy. It really is the best advice anyone can give you.
Delighted to read your post this morning,
Lots of love
Allison