Girlfriend of 8 yrs cheated and broke up even tho i offered a fresh start

Am i dumb for even offering? She was considering but then she was saying how much i neglected her over the years, which is somewhat true i didnt show her the same amount of love i once did, and got too comfty with her and the idea of a future with her. And thats why i offered a fresh start in the first place. She says that she doesnt love me like she used to and now shes distancing herself. What hurts more than this except getting hit by a train? Any ideas what to do?