I don't know if I'd worry about my husband's ongoing relationship with people from before I knew/married him. I would have satisfied myself about that before I married him; did you not know about the relationship? Did he hide/fail to mention it?

My husband was married before me and had lots of female work friends and acquaintances from many years before me but I worked the same place he did and met them and watched them interact and saw more of the "whole" picture and did not see anything anywhere in his behavior (or any of the other women) that would lead me to believe he would cheat on me.