I do not have any personal insight into porn, but there are a few things in your post that make me want to respond. First of all, calling you an "idiot" is really a form of verbal abuse. Name-calling should never be done in a marriage. If this is typical, I highly recommend seeking a godly counselor to help put an end to this.
More than anything, though, know that you cannot "push him" into an affair. Having an affair is a choice... it may stem from problems within a marriage, but it is a choice. Do not take the blame for his actions.
If you have found suspicious things on the internet, I would recommend getting a filter. Also, there are some programs that will alert you if someone in your household has gotten onto porn sites. I had a friend use one of those to confront her husband because he always denied it when she asked.
Remember to pray... for him and for your marriage. If he is willing, go to a counselor together. If he is not, take yourself to a counselor. And, if you have not forgiven him of a former affair but have chosen to stay with him, you do need to forgive him. Holding on to that only keeps the hurt and pain alive within your marriage. You need to ask God to help you forgive in a way that it will never come up again unless he brings it up, difficult as that may seem.
I pray that God will be with you and guide you through this time in your marriage.