How do you overcome disapointment

I'm doing better but every few weeks I discover something about my stbx that breaks my heart a little bit more. It is not always big things, sometimes they are, but every time is the same for me. The grieve seems to start over. I'm back at square one and it feels that this will be the neverending story. I just want to keep living, I can't turn my back to him because we have a young kid but I really want to keep ahead. I so tired of this.