Three games ban is absolutely not happening, of course they will use that to make an example, Pecoraro already told that they will start evaluating the TV footage from the elbow situation until the end and look at them individually. My guess is that Costa would get somewhere between 5 - 7 games ban as a combination of all the incidents (for example 3 games for spitting, 1 or 2 for elbow, 1 or 2 for attempted headbutt or however they judge it), and whatever the number is, he deserves it.
He shouldnt react like that, he did get hit in the face few minutes prior his elbow and the ref should have called it, he may got annoyed about that and the scumbag probably kept provoking him until Costa finally lost control, forgot where he was and went on retard mode.
People also shouldnt react like he raped and murdered a bus of 10 year-old orphans, he made a mistake, did a disgusting thing and now will face the music and meet the consequences of his actions, he`s not getting away with it so at the end of the day justice will be served and he`ll be punished. Its up to him now to come back stronger and try his best to redeem himself. Wish him luck!