[Landlord US-WA] Lodger did not disclose he is keeping a gun in the home we share

I rent out a room in my home. New lodger moved in a month ago. Yesterday I discovered he has a gun in the house. Note that he did not disclose this at all, discovery was because I found a bullet in the washer 🙄

The lease I gave him does not mention guns in the home because frankly, it never occurred to me (yeah, lesson learned there). However I do have a clause that if I feel unsafe, he will move out immediately. I don't feel comfortable living with a gun in my home, and more than that I feel like he really violated my trust but not disclosing that he is keeping a gun in my home. I haven't really decided what I want to do about it, but I've been trying to find any legal guidelines about this issue and I keep coming up empty. Can anyone point me in the right direction on what my rights are, and what my lodger's rights are?

Note: this is a lodger living in my home WITH ME. This is *not* a home that I rent out, while living somewhere else myself. I've had very little luck finding lodging law resources and would appreciate anything you can find. State: Washington.

Edit: I told him I found a bullet in the washer and then asked if there were guns in the house. He said yes.