Not such an odd question, judging from how many responses you're getting. Thanks for being so brave. I will be, too.
My first husband loved naughty sexual adventures, and this was one of his favorites. I told him repeatedly how much it hurt, and that often I felt injured afterward, but his story was, "If you really love me, you'll make me happy." Way back in those days, women were much more strongly counseled to be compliant, and so I would give in.
I don't know why I never turned his argument around and used it on him. If he loved me, he wouldn't insist on injuring me, but would try to make the experience happy for me, too.
Starting before menopause, I discovered I had rectal issues (a rectocele - google it), and for about the last 18 years I have seldom been able to have a normal movement in spite of carefully avoiding constipation. Without getting too graphic, let me say my day usually includes at least one encounter with finger cots and vaseline. Extremely inconvenient and uncomfortable. A forceps delivery may have contributed, and so could my first husband's preferences.
You don't want to go there. Tell him no. He has no right to injure you for his own pleasure. Sex should be a joy for both of you.