Yes. Add your email address to the relevant fields in Settings/Messages (may as well do FaceTime too while you are there) and delete your husband's email address from those fields. You have to add the new one before you can delete the old one, because there has to be at least one at all times.
Your purchasing will still be under the existing account. Messages and FaceTime make no difference to this. This is the exact way I set up m son's iPod and iPad mini. He shares my iTunes account (and credit card!!!) but apart from that, his equipment and mine are totally distinct.