Hi Gem,
First of all

I know exactly how you must be feeling. My DH was diagnosed with Sertoli cell only syndrome a little over a year ago. He underwent a SSR operation to try to find some sperm and despite our best efforts, of course we got our hopes up - sadly no sperm were found. I remember the devastation and finality of being told my DH could never have biological children. I burst into tears right there in the recovery room next to his bed and immediately felt awful for getting so worked up when he was the one who had just undergone a very unpleasant operation and he was being so brave and stoic about it all! I also felt terribly guilty that he had had this procedure all apparently for nothing. I had never even heard of the condition until DH's diagnosis. I started to see all the wonderful things that I love about my DH and grieving for the fact that any children we had would not be able to inherit these from him.
HOWEVER. We are now 16 months down the road and I am very happily 4 months pregnant thanks to donor sperm.

Looking back, both DH and I are immensely glad that he had the unsuccessful SSR because we now know with absolute certainty that he could never have children biologically, it simply isn't possible. Knowing this allowed us to move on to donor sperm in the knowledge that it was the only was we could have children. Olivia makes a very good point in that respect. Although this obviously is nobody's ideal way to start a family, I can honestly say I am over the moon to be pregnant with a donor conceived baby. My DH has been there every step of the way, from the insemination itself, to taking the pregnancy test, to looking after me through morning sickness and holding my hand during scans. I am certain he will be a wonderful father to this baby, it doesn't matter that he has no genetic link to it. There is more than one way to create a family and we will be just as happy, maybe more so, than most.
I hope this gives you some hope for your future journey. If you want to chat some more, I would be very happy to, just PM me.
Best wishes to you and your DP,
Carrie.