HeLp! My husband wants me to do anal.

QUEEN

My husband wants me to do anal, I tried before and it hurt like hell!! Its one of his biggest fantasies cause he loves asses and I have a big butt. So I want to give him that. But I'm so scared because the last time it hurts so bad. and felt like I was pooping. Any advise or tricks I could use to try tonight? he's fine with not doing it until I'm comfortable with it but I want to surprise them for our anniversary.