Well, man, if we're setting ourselves up for horror movie scenarios, in this and similar threads, it's not bad to have in your head the possibility that someday you could get divorced and she could use it against you. Even if she's your high school sweetheart and you've been with her for 30 years. I think keeping the possibility in your head is pretty rational.

Another thing is the decision you make, that in the end, whether you tell her or not is very respectable and there each one has to weigh arguments and decide.