[ChrisV]

Yeah, this is really bad, but luckily you were up against a guy who played even worse. You shouldn't bet 20 times the pot under any circumstances. The guy should just fold everything except a flush and then call and crush you when he has that. Given that you're up against two opponents and one of them has called the flop, I would estimate you're up against a made flush roughly one in 15 to one in 20 times. That doesn't sound so bad - you win the pot 20 times and lose 20x the pot once, so breakeven - until you realise that your overbet didn't steal the whole pot, it only stole your opponent's equity in the pot. That is, even if you check the turn and give a gratuitous free card, you'll still mostly win this pot. Plus, you're taking away the opp's chance to bluff on the river. So all round badness.