My (29F) Husband (32M) Became Obsessed With Napoleon, and I Worry About His Mental Health

I want to begin with saying that he did not show any signs of obsession or a similar behavior before, or at least I did not see it during our marriage of 2 years plus a relationship of 3 years before. He could be too blunt or lack subtlety sometimes but was generally a very logical man with sound judgment. That was until about 6-7 months ago when I found him watching something on his PC. I asked him what it was and he said it was a documentary about Napoleon and his life, battles, campaigns, etc. That struck me as odd because he was never interested in history, politics, or this type of thing before.

He did not change overnight, but gradually. Over time, he started to watch documentaries, videos, and movies about Napoleon more and more frequently. I didn't think anything of it until a parcel arrived at our house. I picked it up as he was at work. The huge cargo was hundreds of books written solely about Napoleon, biographical books as well as books about his wars, etc.

I, of course, asked him what this was all about and he shrugged it off, saying that it wasn't a big deal and he just wanted to learn. By this time he was spending almost all of his free time watching Napoleon documentaries/videos/movies or reading these books. I also saw that the wallpaper of his pc and his phone lock screen, which were previously photos of us together, was changed to paintings of Napoleon. A few days later, another parcel arrived, this time containing huge posters, portraits and paintings of...you guessed it... Napoleon...

I was determined to talk to him seriously the next day after work, when I arrived home I struggled to keep my emotions stable as I came to a house decorated head to toe with Napoleon posters and paintings. All the way from the kitchen to the bedroom, walls and tables were covered. I angrily asked him if he's okay and told him to remove them. He then got overly offended by my remark and acted like I'm in the wrong. I decided to wait until I cooled off. But a week or so has passed and we barely even talked to each other, all the while living in a house filled with those posters as my husband didn't allow me to remove them and got unusually angry when I tried to do so.

Things came to a breaking point when another parcel arrived, containing useless items like a strange hat, which I'm guessing is a Napoleon hat, a replica sword, strange-looking clothing, a pair of tall boots, and a bust of Napoleon. I got furious and confronted him, he completely ignored what I said and asked me stuff like "Is it legal to own a horse in the backyard?" I seriously thought, more like hoped, that he was joking or that this whole thing was an elaborate prank. But he kept a serious face all that time.

I packed my things and stormed out of the house in a moment of anger. I'm at my parents' house now. Just told them that we had a huge fight. I'm seriously considering divorce as he is no longer the man I once loved for quite some time now. We have no kids if that matters. What should I do?

TL;DR: My husband snapped and started watching and buying stuff about Napoleon. We had a huge argument because of it. I'm worried about his mental state and considering a divorce. Need advice.