Okay. Here's what I'd do in your position.

Listen if he wants to talk. And, most of all, BELIEVE him. You don't have to take it as some sort of "literal truth", but it's his truth, and it's his reality, and if he tells you about weird sensations or perceptions that seem really strange to you, just accept that to him, it's completely valid. If you don't fully understand, you can say that, of course, I mean, you don't have to pretend you totally get it (my husband, who has been with me for some sixteen years or something like that - seems like always - understands most of what I tell him, but he only groks about a third of it, and I'm okay with that).

You might also encourage him to keep a journal. An online one would make it so that nobody could "find" it and use it against him, and on most journal sites, you can make it private. I keep a private journal on my computer (private as in "not public"; I don't care if someone eventually finds and reads it), and I have a private journal on Blogger, but LiveJournal works, as do other sites (not sure about Wordpress.com, though a privately hosted Wordpress blog can make private entries). Writing it down can be helpful in sorting it all out.

Here's a true story from my own journey. After an extremely difficult period of tremendous instability (and yes, I got the "she's crazy" thing, too), things started to cool down and my life circumstances started to turn around somewhat. At that time, I had two primary support people, one the man who is now my husband, the other my flatmate, who was a particularly spiritual person (but unfortunately, very young and extremely inexperienced).

I saw, quite to my surprise, that this thing I thought of as "I" didn't really exist. My "identity" was nothing more than a collection of ideas, thoughts, memories, skills, abilities, talents, habits, and so forth. I saw this as clearly as I've ever seen or understood anything in my life, and I was so astonished that I shared it with the now-husband and flatmate. Both of them immediately tried to talk me out of it. And they kept trying to talk me out of it, until I finally just stopped talking about it, but, of course, once you've seen that, it can't be unseen, so I just kept it to myself.

Years later, I learned that this experience of seeing that your material identity is actually transient, transparent, false, illusionary, whatever, is one of the most sought after of peak experiences. Who knew? Not me... and not my support people, either, obviously (the husband NOW gets it and understands it, but it's very much an experiential thing, so I know he doesn't grok it).

Point being, I had a legitimate and well-documented peak spiritual experience and everyone just tried to tell me not to talk like that, because they took it as a bad thing.

So that's why I say just believe him when he tells you stuff. You may not understand, but to him, it's completely real and maybe even downright tangible.

I hope that makes some sense. I haven't really looked at it from this perspective before. Thank you for giving me that opportunity. And thank you for being willing to learn. Not only will your partner benefit, so will you.