I think Momo Adamo committed suicide, because will have even thought of kill DeSimone, only that the boss knew what he had done at the Momo's wife and for sure wouldn't bring much to kill him.
Also shame to hear the soldiers of the family who laughed at his back, and he could not do anything even if DeSimone had violated the rule that prohibited to touch a made man's woman; but in reality, the rules don't apply to who is boss.