Even if it is.... And even if ops husband is truly a sex addict ..... No-one being mistreated, hurt, disrespected, betrayed, their sexual health risked, their mental health affected etc etc etc needs to "stick by" the addict while they seek treatment and see if it's works long-term.
She's already taken 5 years of this - while kept in the dark, and 4 years + while knowing about it. That's nearly a decade of being cheated on .... Cheating is considered a form of abuse, which I would agree while heartedly with.
Ops husband's "addiction" doesn't trump she and her childrens well being, happiness, stability, mental health etc.
As I said, if he's not infected her with something nasty (as well as all the emotional pain and turmoil) it's miraculous. If she conceived any of their kids during those 9 years ... He was also risking their health as foetuses & newborns with possible STDs.
He's had a decade of abusing his nearest and "dearest" .... How long should she keep in being abused.
If anyone knows about his repeated infidelities, op has the humiliation (and the derision for their marriage and family) among anyone who knows on top of everything else
The simple fact is that this man, addiction or not, has not been fit to be a husband, not fit to be in a monogamous relationship (and I'm sure he requires monogamy from op!!!) for a decade - a fucking decade. And will no doubt continue to be so.