Even if he says he's never physically cheated on you and you haven't found anything in his correspondence to indicate that he has, don't take him at his word because you already know he's lying to you. Get tested for STDs and if you're going to continue to have sex with him, insist that he use a condom. He might not be happy about that but your health is more important than whether or not he's offended by the consequences of his own actions.
Also, take a deep dive into your finances and see if there's any shady expenses or transactions. Infidelity--whether it's online or physical--almost always involves financially infidelity as well. Money he's spending on porn, camgirls, or gifts for his online paramours is money that he's stolen from your marriage. If you choose to divorce him, that money could potentially be recuperated as part of your settlement (though you would need to consult with a lawyer about that, of course).
Most importantly, it's very clear to me that you're a victim of emotional abuse--and you need to come to terms with that fact. Your husband says incredibly cruel things, don't excuse his behavior as being too angry or overwhelmed-- those moments are when your husband shows you his true face. He can only wear the mask loving, sad, remorseful husband mask for so long... the more you try to hold him accountable, the more exhausting it is for him to keep the mask on and then it falls off.
At this stage, your goal should not be reconciliation. You need to take a step back from this situation and look at your marriage holistically. Here are a few questions to ask yourself, but this is by no means a complete list:
-Are you the one who is shouldering most of the day-to-day burdens of life in your home?
-Is your husband honest, honorable, and forthright in his dealings with other people in other aspects of his life?
-Is your husband kind, generous, and self-sacrificing, even when he has absolutely nothing to do gain from other people, or is he more concerned with the outward appearance of being a great guy?
-Are you the one who is always backing down in a conflict, always seeking to make amends, and apologizing?
-Do you feel respected, understood, and validated by your husband?
-If absolutely nothing in your marriage changed, could you see yourself living like this for the rest of your life?
BW, 40s
Divorced WH in 2015; now happily remarried
I edit my comments a lot for spelling, grammar, typos, etc.