Okay, once and for all, why did yoda run away in ep. 3 when he'd knocked sidious off the platform...?

this, after absorbing all the force energy sidious had thrown at him. just before they both fell, yoda had grimaced and appeared to get "angry" and deal out a shot of his own. then, yoda fell(why could he not break his fall using the force?). query why yoda felt he'd failed and then had to go into exile...is it bec he lost his temper which, as the head jedi would be conduct unbecoming? serious, knowledgeable answers only, please....