Husband reveals Friends with Benefits Relationship ...from the past?

[M K]

My husband told me that is ex (and mother of his child) was a woman he never loved & was with her for the sake of their son. (this was a casual relatonship). I believed this because he is a good father & did things for the ex to help her out at times. When I met my now husband, he had been broken up with his ex for 3 years at that point. He tells me that for the 3 years that they were "broken up" they maintained a "friends with benefits" relationship & it stopped because he met & fell in love with me. This "news flash" bothers me and makes me feel like I was misled about his past relationship. Why would he sleep with her for years? Am I being ridiculous to let this bother me or am I right to feel mislead?