Jones, I am so sorry this has happened to you and I am so sorry you feel under attack here. What you are feeling and going through is perfectly natural, predictable and understandable. It is very familiar.
The first thing to do is take care of yourself. Of course you and your husband are individuals and your relationship is unique and no one here knows you.
But if you were to read around the matter of affairs discovered and infidelities there is also something glibly referred to as 'the script' (for both cheater and betrayed) which is a set of things that almost every single person in this horrible position feels and says.
The first reaction of almost everyone who discovers an affair in an otherwise okay relationship is shock, anger, fear and an immense desire to hold on to the marriage. Because the fear of change is too much, and also because the cheater has a 'one up' position, they have a sort of choice, even still, to stay or leave, and to still have a partner either way. The betrayed is blind-sided and still used to relying on their partner in times of great distress, including this one. The betrayed also recognize that the marriage was not terrible and that the affair may have little of with the relationship, but a lot to do with the cheater and their personality.
Also what tends to happen is that a couple who have been incredibly emotionally distant for a long time (because the cheater has wanted to do this to give an excuse for the betrayal, and out of loyalty to the OW) begin to talk again, honestly. This is extremely powerful and can produce a state called 'hysterical bonding' where passion, emotion and sex can be on the agenda again after being gone for a long time. This is a combination of relief on the part of the cheater, desperation on the part of the betrayed, and an adrenaline shock generally as the pair feel intimate for the first time in ages and 'seen' by each other.
This is a useful but temporary situation and should be recognized as such.
The cheater is very often in a situation where they love two people. Most commonly the cheater will downplay the affair in this period, for fear of hurting the betrayed and whilst he works out what he really wants to do. He/she will be in contact with the OW, and if he is in love with her, will make gestures suggesting that he will leave to be with her once it is 'worked through' with the wife and she is not vulnerable any more. He will claim to want to make the marriage work immediately, out of fear of upset and because part of him definitely does want to do that.
If he does not love the OW, he will drop her like a stone and concoct a story about how she was obsessed with him and begin to paint her in very unflattering light in case she gets in touch with truths that he can claim are inventions.
At this moment, you are in absolutely no position to know what you want for the long term (nor should you be) and you do not know the truth about what he wants either, neither does he. Until you discover the truth about WHY he had the affair, both the reasons he tells himself, and the more truer one, beneath it, you will not know who he is completely or what your relationship needs to do to recover.
The reason people are maybe unhelpfully being aggressive here is that there are some very important things that can make the difference between saving a marriage and setting oneself up for a continued torture of adultery. One is that he should immediately show you the correspondence between them past and present if you want to see it, so he cannot lie about the nature of that. (he will at first lie about being able to access that. Everyone keeps emails. Everyone.)