Your husband is telling the truth. Regardless of whether you've had children, or done exercises, your anus is tighter than your vagina. Your vagina was designed to allow a baby to pass through it. Your anus was designed for a smaller capacity.
Hmm. Once you are able to learn to relax and with lots of lube, the anus may not be feel much tighter than a vagina. In fact, once you get past the the anus itself, things get pretty loose, and it can feel much less engulfing than a vagina. Kind of like a rubber band at the base and then nothing. And, pardon the pun, but I never seemed to bottom out as I do with a vagina.
IMHO, there's nothing abnormal about a man liking anal, but given your history of tearing, it seems that should be considered by your husband. I can't make medical advice, but patience, communication, and lots of lube are critical. From my experience, if it's tight enough, there may not be enough lubrication.
I know the number of kids born impacts things, but my experience has been that the Kegel exercises really work. My wife had two children, and she's far tighter than well lubricated anal I had in the past.
As for women preferring/liking anal, I have had different experiences. I had accidental anal with my first girlfriend, but wouldn't do it again. A college girlfriend was an anything-but-vaginal-saving-it-for-marriage person who managed to orgasm with very little stimulation during anal. My ex wife and I ended up with very infrequent sex, and it was usually anal as she had vaginal pain post hysterectomy (long story). She'd come about half the time. My wife is a "don't go there" kinda person, and I really don't feel like making it an issue, as everything else is great. So I don't go there.