Communication is vital right now. It is important for you and your husband to talk about how you are both feeling, why you both feel the affair happened, whether or not he wants to save the marriage and what the two of you are going to do to get your marriage on the right path. Communication means listening and talking. I mean listening, while your husband is talking to you turn your brain off, stop assuming you know what he is going to say, don't sit there and think about a response to what he is saying... actually listen, hear what he is saying to you. You may not like what you are hearing, but you have to listen. Try to remain as calm as possible and talk.
Understanding, while communication can be difficult when you are hurt and angry... understanding can be even more difficult. Surviving infidelity in marriages means knowing that there is a difference between understanding and acceptance. You don't have to accept what your husband is telling you, you don't have to agree... but you do have to understand, just as he needs to understand where you are now. Saying "I'm sorry, it will never happen again," and then moving on is NOT going to save your marriage. It is important that the two of you understand how and why you got to this point, how each of you are feeling right now and how you are going to move forward.
Responsibility, another tough pillar, but in most marriages an affair is the result of the two married people not being fulfilled. Surviving infidelity in marriages means asking is your husband is happy. A happily married husband, who feels needed, appreciated and desired, is far less likely to cheat than a husband that does not feel that way. If your husband isn't feeling this way you are going to have to take a step back and look at whether or not you are making him feel that way and how you can start. Don't assume that you are successfully making your husband feel needed, appreciated and desired, ask him what would make him feel that way.
Finally forgiveness and this one won't happen overnight. Actually none of these "pillars" are going to happen overnight; they are going to take time. At some point though you are going to need to forgive your husband... and yourself because this is the only way you are going to move forward. You have to rebuild trust, which isn't easy and is near impossible if you don't forgive the person that hurt you. Coping with infidelity is hard, but if you can follow these guidelines you will find that surviving infidelity in marriages is not only possible, but it may actually make your marriage better.
There are even more effective steps that you can take to get past an infidelity in your marriage.
These additional steps require more room to explain than what I have here. Instead you can get them on my website Infidelity In Marriages