Please help me I am hurt for no reason

my boyfriend and I have been having anal sex for over 3 1/2 years we broke up for 9 months and started all over again. We had anal sex for 7 months straight I would say 5 times a week for 5 to 7 hours at a time. I Didn't see him for a week and when we had sex he said my butt is wider and deeper and accused me of cheating on him which I never did I took a lie detector test and everything proved I didnt cheat and he keeps saying what happened to your butt and I keep saying I didnt cheat I took a lie detector test. He will not accept any thing except for me to tell him what happened to my butt and I have no answer to this I didnt cheat I dont get it can you please help me explain to him the effects of extreme anal sex like we been having. Help please.

Yes this is genuine and I am truly hurt over this.

I am hurt over the fact that he accused me of cheating and doing something so degrading like have anal sex with some random man. I loved him and that is how I expressed my love to him. I took a lie detector test and he still says I cheated. Do men not understand that if you are constantly having sex that womans body is going to change. All I want is.an apology for degrading me