You have noticed that your partner has been engaging in unhealthy sexual behaviors, and suspect they are a sex addict. You think they should get help, or at least admit their issue so it can be addressed - ignoring the problem will not make it go away. Here are some things to keep in mind if and when you choose to confront your spouse about their addiction.
Confronting the sexual addict should be done in a deliberate, mindful, and careful way. Do not approach them with anger or accusations, as it can elicit a defensive response instead of a productive one. In order to make your partner feel less attacked or cornered, try to use "I" statements, instead of "you" statements. This emphasizes your own feelings and needs, and shows the impact that their addiction has had on you as their partner.
Try to remember that even though their addiction has hurt you, they are still a person who you love and have a deep relationship with. You have the right to feel angry and hurt, but try to express these feelings with compassion. Let them know that you love them and only want the best for them. Offer help, and encourage them to seek counseling or group therapy so they can better themselves and help your relationship.
"Constructively Confronting a Sex Addict" by Kay Jones