I've worked on myself in recent years to become less and less "offended" by things that really don't matter. I've been called a slut in a nice way, and a few times in a not so nice way. If I "get offended" and the person meant offense, they win. Right? So, I simply laugh. If My Man uses it in dirty talk or just messing around, "C'mere ya little slut!" I find it arousing or funny.
I used to be the type of person who would look for things to "be offended" by. It was wasting a LOT of energy and effort on my part. So, I have worked on my feelings so that I only become offended by truly offensive things; say racism, slavery, pedophilia etc.
It's just a word. Eleanor Roosevelt said something to the effect that one must give permission to allow someone to degrade you. If you don't give them permission, their words have no impact.