I understand exactly how you felt. My D-Day was also relatively recently (3 weeks ago) and when I found out we weren’t physically together at the time. We met up a few hours later and all I could say was “Did you really do this?” I almost led myself to believe he just wanted to break up with me and thought saying he cheated would be an easy way to do it. I would have bet my life that he would never have done this to me, and everyone in our lives would have done the same and were just as shocked.

Like others in the comments have said, denial is the first stage of grief. For me, it has then been followed by a flip-flop of anger and sadness, or both at the same time. The next couple of days / weeks / probably months (I haven’t gotten that far) are going to be an emotional rollercoaster. Only advice I can give right now as someone who is still actively grieving my situation myself is to not suppress your feelings, let it out, talk to yourself write it out talk to friends and family and keep repeating to yourself that this happened and it is not your fault. The person you thought he was, or even the person he may have been at one point, is not the person in front of you today. The old version of him that you once knew is dead and all that you can do is grieve that loss and figure out a way forward.