Having a very hard time coping with male infertility

My fiancé and I have been trying to conceive for 3-4 years. We finally have some answers. He has a lower sperm count but the main problem is that the sperm have a very low motility. Our infertility doctor says the next step is insemination and of course can't guarantee that'll work. He says my fiancé may not produce enough sperm for that. If not, we'll have to go with IVF. So far we've learned there is nothing known to be "wrong" with me - meaning there's no reason I personally couldn't get pregnant..the issue is my fiancé. I'm having a very hard time coping with this whole thing and trying to figure out what I should do. I love this man...I planned on saying "I do" to this man and planned to be with him forever and that love is supposed to mean unconditionally...but deep deep down in my gut I can't help but blame my fiancé..even though it's not his fault he has this problem. I want to stick with him but at the same time I feel like a horrible person because I know if I stay and our treatments are unsuccessful, I will resent and blame him for the rest of our lives. I want to be a mother so badly it hurts and knowing I could be one if it weren't for this...it just breaks my heart and I have no clue what to do. I already feel bad enough, so please keep any negativity to yourself..I'm just looking to hear from anyone who understands and has gone through this too. 😭