I found out this week I'm sterile. I don't know how to break the news to my fiance...

Whatever you say, sterile loser. It was all for nothing, and this was all preventable.

Don't marry anyways, you dodged a bullet. Use the money you would've on a kid, and eventual divorce rape and buy yourself something nice. Fuck, you don't even need to pay for a vasectomy now, so you can nut guilt free in any girl you want.
But yeah, let's just cry over the fact you can't be a slave anymore instead.