My response was to the fact that you said it was THE most intimate experience and so on.
I find that to be very sad. Intimacy should be way more than physical pleasure.
Anyway...you may have done it without ill effects but that doesn't mean it is a safe thing to do. Many people snort cocaine without anything major going wrong but all it takes is that one time for your heart to react the wrong way and poof! You are gone.
Similar with anal sex...you do it enough your sphincter will lose it's tone and you will lose control. You may not have contracted any type of infection but the more you expose yourself to the act the greater your chances are of it happening...just the law of averages. And it gets more risky the more comfortable you are with it because you let your guard down.
Then there's the moment when the force of your partner's thrust tears your colon....ouch! That's gonna be a mess. Dangerous to expose your innards to all that bacteria too.