The other Justice Leaguers had actually found out before this; this was the moment he came clean with the public. But they reacted in different ways. If you want, I can scan in the panel from this same issue wherein the Blue Beetle calls him "Captain Traitor." On the other hand, Red Tornado and Power Girl remained his close friends.
As for how the public reacted, they were pretty angry. Unfortunately, Cap's series was canceled not long after this, so there was never a chance to explore in any great detail the fallout from these revelations. Moreover, the seven issues that were left after this were written by different writers, most of whom were just killing time before the end, and who did not really get the character.