Unexpected pregnancy

We have been married almost 7 years and have a 2 year old.  We have had our ups and downs over the last year and discussed we were not quite ready for a second.  I went off BC in February because of hormonal issues, but we are always "careful", however full well knowing that unprotected sex could always end in pregnancy.  However I have also had a lot of problems with sex drive, so we haven't been very active... At all.
Well, on our last night in our home before we moved we weren't as careful, and apparently that's all it took.  I just took a pregnancy test because I just had a feeling, and sure enough, I'm pregnant.  
I know my husband WILL be excited... Eventually, but I am scared of his initial reaction. Neither one of us were ready yet.  Anyone experienced something similar?