Large penis with an IUD, help!

I am talking to this guy who has very large penis, about 9.5" and very girthy (like makes girls cry big) I have had my fair share of large dicks and seem to do ok, yet I am worried my IUD will become dismantled and lost in the abyss of my uterus if he nails my cervix by accident. I'm hesitant to have sex with him until I get some answers.