Janadele

Staistically speaking if you marry someone from another culture your chances for a successful marriage are not as good. But spiritual confirmation trumps stats any day. Good luck.

What Kimball said is very true; however I would be extremely cautious.  I would get to know his culture extremely well and I would be prepared to make some sacrifices.  For example, what if he wanted to move back to his home country?  Would you be okay with this.  Other cultures have very different views of male/female relationships.  Without knowing your background it is impossible to guess, but latinos for example have a very macho culture.
 
In general get to know his family extremely well, get to know how he was raised.  If there are things that make you uncomfortable now, be prepared b/c in general if it makes you a little uncomfortable prior to marriage when the love bugs are flying it will be very difficult after the infatuation wears off and the real work of marriage begins.
 
If he is of a different religion then you've got several strikes that will make marriage very hard.  Is it doable? Sure, but in general the closer your husband's culture matches yours the better.

I couldn't imagine any scenario where I could sleep in the same room as someone I didn't know really well and trust them not to murder me in my sleep

Joseph Smith was a holy man.  I have no doubt of this.  

Ultimately it is a choice...  You can chose to remember and believe whatever/all spiritual spiritual witness you have received up to this point about God, Christ, the Book of Mormon, Joseph Smith, modern revelation, etc.  Or you can choose to let it all go in the face of this new information.
 
Remember that God has always known the truth about Joseph Smith and the church.  Between you and him you are the only one that did not know this the entire time.  So while this is clearly affecting you it does not in any way invalidate the things you have already received from the Lord.
 
So the question is... How much are you willing to trust the Lord?