Is OTHER wrong in the post ? POST : Obligatory this happened a few months ago and sorry for formatting I'm on mobile...

Just some background... My sister was skinny for most of her life but now that she is out of college.. She has gained some weight and is really self conscious about it. One night, we were going to dinner and she came out with a white, puffy, faux fur sweater. Without thinking, I said that she looked like a polar bear. I didn't mean it because she's fat, just because her sweater looked like polar bear fur but everyone looked at me like I had just killed someone.

Months later, my mom still brings it up to me about how bad that was to say but I honestly didn't mean it to be rude... Am I the asshole? 