Let's assume, just for the sake of argument that LFC gf name is Elizabeth (I have no idea).
Instead of saying anything about bitcoin, retort by saying "Liz and I are thinking about splitting".
They would leave you alone and converge on a "poor Liz".
A risky proposition, perhaps, as some "retaliation" and sad face might follow, but maybe needed for the future opsec.
Otherwise, things would go out of hand shortly.

Thankfully, my wife is very discreet about it. We never tell anything even to our children.
Eventually, they would know, but not yet, although there could be some debate about this as their life path could be different (or not).
My worry is that knowing anticipation of the future 'reward' might result in the current passivity.