Others have given you good advice. Having been through a divorce (not my choice, and neither porn nor infidelity were factors) and counseling, I can offer some perspective.
Firstly, you have justification to separate (you'll have to decide prayerfully for yourself whether you have a mandate to divorce). Separation in a Christian context should be time apart to change the bad behaviour (where appropriate) and to heal, with the intent to renew the marriage. It only works if both of you are committed to healing. That's the best time for individual counseling.
Secondly, you must forgive your husband.;
you will not heal until you do. He doesn't deserve it, but that's beside the point; Jesus forgave you when you didn't deserve it.
Thirdly, you would do well to create, set, and enforce some "boundaries". I recommend Cloud and Townsend's book by that title.
Fourthly, maintain the separation until your husband
demonstrates that he has changed and owns his behaviour without excuses. Don't accept apologies as repentance; they are different things.
May the Lord give you His guidance in this difficult time. He IS faithful, even when people aren't.