As uncomfortable as it might be, one of your first steps toward repairing your relationship might be some honest self-assessment. Did you do – or not do – something that made your partner react the way he did? If you don't share his interests, you may have refused to budge about doing the things he enjoys, so he found someone else to share them with. You might be a workaholic, rarely and grudgingly giving time to your relationship, so he found other ways to amuse himself. If you can figure out whether you had any complicity in the problem, and if you can accept some of the blame, the betrayal becomes something you and your partner share. Finger-pointing becomes less of an issue, even if what he did is far worse than your own actions.

It's probably impossible to go forward by pretending that nothing happened, nor would it be particularly healthy. Your partner's betrayal would always be between you, a shadow you're both aware of, but that no one mentions. Talking about what happened is vital and can create a new closeness, but Coleman warns against beating a dead horse and discussing it relentlessly. Set limits, such as by acknowledging that you already rehashed the subject once today, and so, you won't do it again until tomorrow. Another option is to stop yourself after you've talked about it for 15 minutes or so. These conversations should continue until you – as the victim – feel ready to let them go. If your partner is not willing to discuss his violation of your trust – even repeatedly – this may be a sign that your relationship isn't worth saving.

Your partner is also going to have to accept that it will be difficult for you to take anything he says or does at face value for a while. Experts such as Coleman say the usual rules of a relationship change after a major betrayal. It's up to your partner to regain your trust by making his life an open book, effectively proving himself to you again. This may mean giving you unfettered access to his cellphone or checkbook so you can see what he has been up to. Reassurance – particularly over an extended period of time – will help you learn to trust him again, and this is a vital component of maintaining your relationship.

Accept that you're probably not going to be able to travel this road alone. If you have a tight network of close friends you can vent to, that's great, but your friends aren't professionals, with the knowledge and training to help guide you over the hump. Consider therapy, at least long enough to set you on a path to recovery. Your partner may or may not want to attend counseling with you, but even if he doesn't, it can buoy you up if you go on your own.