The other players in the field went after you, not Bernie, because they’re afraid of Sanders’ oh-so-Trumplike Bro and bot army. They think attacking him will “depress turnout” or that it will “divide the party” or that they’ll “need his voters later.” Hillary Clinton thought that and didn’t do what needed to be done. She believed to the last he would help her campaign, and he didn’t.
There’s nothing he has in terms of support that you can’t buy, build or substitute with other voters.
Here’s the irony: You’re the only one in the party who can stop him, and you’re the worst possible candidate to do it. Everyone else who was snapping at you on that stage was conscious of the fact that Bernie is the real target, but you were the tempting target.
You need to educate Democratic voters to the hard fact that Sanders will lose to Trump, giving you two bites of the same apple: purging the Democratic Party of its poison while also keeping up your brand image as the Trump slayer.