I disagree about the sexism. It might be there in dog whistle form, but his primary reasons for what he is doing isn't about sexism, but about hiding his own faults.

Hillary Clinton (with one of the strongest resumes in history) is called unqualified twice by Bernie himself, despite her being more qualified than he is by far.

This is an act of deflection: Sanders admitted to this himself when he claimed that he said this a retaliation to her "comment" of his being unqualified, and all this despite him having expressed that he respects her later on. She said the truth about him not doing his homework, and he responds with a lie about her. And he also didn't bother to read her original words, further showcasing a low limit of his qualifications (for which, he again deflected the blame onto someone else, the media).

Saying that Hillary's "ambition" will destroy the Democratic party

Criticizing her ambition is a criticism of own his ambition. Does he have enough? Is he sufficiently motivated to do what needs to be done to be an effective president? His lack of support for democratic politicians facing their own elections, is this a way of showing how he is good for the party?

What is his plan for passing his agenda if he becomes president? Because being an ineffective president will hurt the party. Because if he has few independents and democrats in congress, he will need to make a devil's deal to get anything done. On that note...

Weaver stating that Hillary has made a deal with the devil and that he will get his due

Well, Sanders would know best. He compromised his morals for the sake of truthfully representing Vermont citizens when it comes to gun issues, and now he is being criticized for it, and to some lesser degree, blood is on his hands. He compromised his morals by joining and using some of the supports of the Democratic Party, who is partially funded by what he would consider dirty money. The devil will be waiting for him, yo.

Compromise is a necessary evil in politics, and he should have realized this before walking into the pre-presidential limelight.

Politics is not a place for the morally meek, and what I've seen from him this week are the stomping of the feet of someone who didn't do research about what he was walking into, and making coward's choices.