It is natural to be in such a period to seek help from a specialist. Professional psychologist can help you not to get depressed and at the same time get rid of negative emotions. Thanks to the participation of another person, you might be able to in another look at the situation and did not perceive all become so painful. Parallel to occupy yourself with something that you like best or what you've always wanted. This can be a hobby or a sport, just a week in shopping.
After the emotions calm down, and the first pain will pass, you will need to talk openly with your partner and find out what exactly was the reason for committing him or her. It is possible that in some ways there's your fault. This, of course, in no way takes responsibility with the "criminal." But such a scenario can help both of you to take the path of rapprochement, if you both really want this. In any conflict both sides are guilty and you should not pass the buck to one. Be critical to yourself, too, and try to understand what you want. If the partner sincerely repents, are you ready to forgive him and give him a chance again?