Hi vintage. You caught your DH having an affair. Affair of the heart, emotional affair, work spouse. There are different names for them. They are all a type of affair if one spouse develops a special emotional connection with another person without notifying their spouse. You are angry and its normal and you should be.
Work on getting yourself better. Find ways to sort your selfout, get your self esteem back and feel better about yourself and who you are. Then open the door and start to talk. It might take some time. I went through this in Jan of this year. It took about a month and a half to get through it. There was crying, loss of appetire (I lost a lot of weight and look great!) , loss of sleep, feelings that my life is changing and over forever. Its because of the emotoinal betrayal that the EA caused. You greatest trust and stability in ones life is their spouse, family and house and you build protection around that in your life. An EH is a attack on that stability and foundation from the inside of the family and house and it shatters the stability you thought you had.
What is important is that once you decide to talk about it, be on the lookout and find out what he is willing to do to change things. Be on the lookout for any signs that he is just waiting for this all to settle down and his life to go back to normal so he can go back to conducting his emotional affairs and be more careful about you not finding it. It means he is indifferent to what they are causing to you and is indifferent to your feelings. That's not a good sign for the future. Going through this experience is mentally and emotionally taxing. There is a lot of anger, loss of self esteem, loss of sleep, loss of appetite. Its an emotionally taxing and mentally taxing roller coaster of a month or two and an adult doesn't need that sort of stress in their life in addition to other things that go on in life. He needs to be aware of what his actions caused and he had to come to his senses that its not right to make his spouse go through that.
FWIW, my own situation is, its been almost 2 months. I feel I am over it. I am able to sleep normally. But things aren't the same anymore for me in the marriage. I went through the phase of blaming myself for what my spouse did. I am now at the stage of seriously looking at the marraige for what it is and what it has become and am having feelings of indifference as to the future. This is mostly due to the fact that my spouse seemed to have been very indifference to what the emotional affair cause me. S=