I'm an (almost) infertile male. Tired of coworkers asking when I'm having kids. Advice?

Wife and I have been married about five years. Been trying to have kids for two, and hasn't been working. Just had all the medical tests done and found out that I'm rocking less than 1/20th of the sperm I should be. We can likely have kids, but it's going to take procedures and be expensive, we're just starting down that road.

Since I got married, every fucking person I work with (male and female) ask me god damn near every week when I'm having kids. I've tried humor, passiveness, laughing it off, etc. They won't leave me alone about it and now it's getting on my nerves. I haven't even gotten up the nerve to tell my family about the problem yet. Our company Christmas party is coming up and I know everybody is going to be asking my wife about it (she's already sensitive about it). I kind of just want to tell the next person who asks that we can't have kids and thanks, by the way, for fucking harping me about it for five years. I'm thinking there might be a better approach. Tips?