Anal sex hurts because the anus is not made for sex. It is made for evacuating the contents of your colon. With that being stated, the obvious is at play here. Do you REALLY want this, or is it b/c your husband wants it and you want to please him? There is no way to make this a "natural" event without discomfort/pain. Sorry luv, no advice here but to refrain from it and stay with what has been working for you.
I would be concerned about ecoli as well, and the spread of it. That is nasty business.