Awww, hon - CONGRATS on your pregnancy!! I read a couple other threads and I thought you were, but didn't see an official announcement!
From the posts you've made about your BF, he sounds like a really great guy, and it will take more than mood swings to scare him off! He's around for a the long haul! I'm sure he knows that you aren't meaning to attack him and that it's just your hormones coming into play.
I don't have any good advice because I've been super lucky as I never have mood swings, even in my periods, or currently in my pregnancy. DH doesn't realize how lucky he is? Maybe you can apologize by baking him a batch of his favorite cookies and a gushy card about how much you love him?? Bribery always works with my DH!
!