If you are the cheating party, you need to end your affair completely before you can expect to have any chance of healing your relationship with your partner or spouse.  This step is non-negotiable. If you cheated with a co-worker, for example, you may need to consider seeking re-assignment or even finding a new job.  An affair that started at the gym or in another social setting may require you to change your social habits. Tell your partner what happened and why. You can tell your partner the intimate details of the sexual experience if he or she asks, but it could be too painful to reveal at first. Your partner may not want to know at all. This should be a choice your partner makes, and you should abide by your partner's wishes.  Your partner is likely to lash back when presented with your painful admission.  While your infidelity will form the core of your partner's hurt, you may find yourself confronted with a whole range of issues as your partner seeks to express his or her pain.  If your partner has ever had an affair, news of that infidelity is likely to surface during this initial exchange.  Responding with disclosure of this information may be the closest weapon your partner has at his or her disposal.  Be prepared for such an admission, and remember that if you feel hurt by disclosure of such information, your hurt is paralleled by your partner's pain regarding your own infidelity.  You'll both have significant healing to do. Spend time diagnosing the reason for your infidelity.  A wide variety of reasons may have contributed to your affair, from low self-esteem, alcoholism, and sex addiction to the pressures of marital problems or perceived deficiencies in your committed relationship.  Conventional wisdom once argued that infidelity was always a sign of something missing in a relationship; it is important to recognize that professionals now believe this is only one among many reasons why people cheat.  Regardless of your reason for cheating, you should never blame your partner for your decision. ...

TL;DR in Vietnamese:
Ngừng lừa dối. Thực hiện những thay đổi cần thiết để tách bản thân khỏi người mà bạn ngoại tình. Thành thật với nửa kia. Thành thật với chính mình.