Posted on infertility too but looking for more relationship based answers, I think.
DH has always known he had fertility issues. He's been honest with me from the start. I didn't take this lightly at all but decided in the end I wanted to be with him. Assumed we'd go through everything together and take it as it comes.
Now we are looking at TTC, he said to me "I'll have any test you want me to have". Thought wording was a bit odd - it turns out that he doesn't mind having a test, but he's scared - shit scared - of knowing what the result is, so he thought that he could go for the test but only I could find out the results and not tell him 
He's going by garbled, cobbled together information from his family and has made his mind up what his "condition" is and doesn't want to know if it's worse. I'm frustrated by this, I don't want hearsay, I want to speak to a doctor. From internet research into the condition, it results in a chance of abnormalities, but depending on which kind he has, will decide whether the foetus is viable, causing disabilities, or not, causing miscarriage. We can find out which with a simple test and it's really upsetting me that he doesn't want to. He says it's like having a test to find out whether in the future he'll get cancer. I feel like avoiding it is like not finding out whether you've got a chance to avoid cancer.
I feel like he's made up his mind (he wants to just try, as normal, to have a child and assume everything is fine unless it's not happening) and he's just handed over responsibility to me. I feel really crushed, like we're not making the decision together, like the weight is all on my shoulders, like he's sticking his head in the sand.
I get that it's more emotional for him than it is for me since it's all tied up in him being "broken" or potentially harming our future child, and I get that he's had around 10 years to think about this whereas I've had 3 to think about it half heartedly and these last couple of weeks/months to really stare it head on. I said maybe I'm being selfish and he said that he thought I was. He later apologised for that.
We've talked again since this and I asked if he would be up for going to a meeting/discussion with a doctor, or a geneticist, to ask what options we have and what if anything we can do to reduce any risks. He has said yes, but I don't feel like he's going to go in with an open mind. He's already made up his mind that he doesn't want any kind of test. I suppose I'm hoping that this might change his mind which is silly. But then maybe they will bring up other options which neither of us have considered.
Has anyone ever been through anything like this? How do you deal with something like it? I feel stuck between a rock and a hard place. I think he's being selfish, actually, but then I can't be mad at him for being scared. Argh. I'm less upset than I was earlier and I feel like we've got somewhere but I'm worried that it won't change anything and we'll be back at square one.