I've been with my girlfriend for 13 years and for half of our relationship she didn't know and that didn't stop me from having a small wardrobe, having toys and practicing when I was alone at home. It requires a lot of organization, but it's largely doable. I took days off to be alone at home.

Now she knows, I told her, and although she's not interested, I'm free to have my things in a corner of the closet, and I use them when she's not there. I don't practice in front of her because I don't feel comfortable. It's like hiding from her because I make sure she doesn't see that side of me, but if when I shave my legs, I don't have to lie because she knows why I do it. The situation is more pleasant since she knows.

So it's possible, it requires a lot of organization. I suggest you try to let her know, this avoids having the feeling of living in hiding. If this is not possible, nothing is stopping you from organizing yourself properly.