I think Hottimes brings the right perspective. Given sufficient practice, I suspect many women can take more anally than vaginally. Certainly the world of porn, and the size of widely-sold butt plugs, would suggest so.
I think you can both have what you want. Your husband doesn't have a "circus-sized" dick, he's got a large dick.
With some practice on your part you can almost certainly take him.
Just imo, and best of luck to you both.