Slut is our preferred term. She calls herself a slut, slutwife, cumslut, etc. and is 100% OK with me telling guys they can fuck my wife because she is a slut. She loves to be called a slut by the guy(s) while fucking her.
Bitch doesn't fit. She isn't a bitch. Even when someone isn't balls deep in her she is still well-liked.
Same for whore. We associate the term with a woman who is messing up her own marriage or other people's marriages or with a woman who fucks for money. She does neither.