Hi and welcome ,
I don't there is going to great, perfect, way to drop this news.
Do you have kids? That generally weighs into these decisions on both sides.
The upside is you are only 3 an half yrs in. I think knowing this kind of stuff is alway better sooner than later. And looking back at hypotheticals isn't going to help either one of you move forward.
I'd do you reading and research in the open and answer the question if and when they come. Frame it as exploring an interest...that can morph into hey I think I really identify with this ...go from there.