There is a big difference between a person occasionally viewing pornography with the knowledge and even involvement of their partner to a full-blown betrayal and using adult websites to start affairs with other people.
There is a good chance of success for the two of you, if your husband accepts responsibility for what he has done and if the two of you are willing to work hard on improving your marriage.
This should be time you have alone perhaps when the children are in bed and to make sure it is distraction free (with the computer and TV turned off).
In addition, try to have at least one special evening a week when you get a baby-sitter when you can do some new things together. The biggest prize of a successful marriage is closeness and intimacy – which allow a couple to accept and support one another on a deep level.
Relationship counselling agencies report that a growing number of couples are now seeking help due to infidelity online or to one partner accessing adult websites.
How much of a problem it is, depends on the degree and type of access and what it means in the context of the marriage.