He asked for divorce now a he’s crying

STBXH cheated with co-worker ( kissed her) he confessed to me and i worked through forgiving him, once he had my forgiveness he then decides he doesn’t want to be with me and asked for divorce. I agreed and have been healing and moving on for months. Now he’s crying secretly and says he can tell I don’t care anymore. I’m confused! How do you ask for a divorce and then be sad that I’m not crying over him anymore. I’ve been to therapy and reading and spending time with friends and family Etc. He’s done nothing to work on himself because he knows everything and doesn’t need help. So why is he so upset, why isn’t he relieved that he’s free and I’m not trying to make anything hard for him? I just want to move on. We do have one son and have to live together until the house is sold. We have talked about splitting up all assets on our own (all amicable) and will do the divorce without an attorney, so for the most part this should be a clean break, only thing has to be decided is child support and how we will split our time with him. But I’m curious about this behavior, any insight is appreciated.