Kids eavesdrop. No matter how hard you try to keep things from them about their disability, they will eventually succeed in overhearing you.
The time kids are most likely to succeed in eavesdropping is when you are the most upset about their disability — because being upset and overwhelmed takes a lot of energy, and it makes it harder to pay attention to keeping kids from overhearing.
Further — kids these days have access to Google. When kids overhear adults talking about their disability, they are likely to investigate by googling it. The first result for their disability is probably *not* what you want your kid to believe about themself and their future.
Talking to your kids about their disability is much better than letting them find out about it from googling what they overhear.