It's okay that you don't know how to move on. Start with something easier... like not going back.
Sometimes we over-complicate the process of moving on. Or, we're hard on ourselves when we want to move on and we don't exactly know what to do next. Sometimes just by not going back, or repeating what you want to walk away from is an action in the right direction. You don't always need to replace an action with something else. Sometimes no action, stillness and not going back are the best coarse of action.