What is the best way to confront your partner that you suspect is cheating? Well, it's never easy. One thing I tell people is that suspicion is not enough. If you have just a mere suspicion with absolutely no facts to back it up, it is not a good idea to nag or upset your partner with this suspicion. I think you need to have facts and some documented evidence. And if it takes getting a private detective or collecting more evidence before confronting, I think it's very important to do that. Because if it's a mere suspicion your partner may simply hide it and get better at hiding the affair.
So get your facts straight. I would also talk to someone who is impartial and who can evaluate this evidence. Whether it's a therapist, whether it's a good friend. Someone who you can share this with, share your feelings with so you can be calm when you confront your partner. And the important thing, when you do confront your partner, do so calmly. Lay out the facts, do not judge, no name calling, and listen. Prepare to listen, not to interrupt. Just let them talk. And I think it's very important this nonjudgmental listening to be able to elicit as much information and elicit the feelings behind the affair.