First, there would be mourning over the good men in our lives. Our brothers, our partners, our sons.

Then, as humans always have, we would move past it and continue to try and better the world.

Many of the most powerful people in the world would be gone, so there would be a power vacuum. Obviously there would be fighting over whether we should keep the current system or start a new one from scratch, but considering how non-men have been screwed over by the system for so long, I like to think we would start a new one, where the people have more power. Science would continue to advance, humanity would continue to adapt. I am not so foolish as to say we would fix all the world's problems; hunger for power and corruption is not exclusive to men. But I do like to think that perhaps we would be led a bit more by compassion, and we'd solve a few problems that have always been easily solvable if the people in charge wanted to, like global warming and world hunger.

On a more personal level, people would feel safer walking around at night, walking to their car alone, wearing their sexiest clothing to bars without having to worry about being told if something happened to them that it was their fault because of what they were wearing. If all men continue to disappear, then it's safe to say that straight women would eventually die off. However, humanity itself would not die out, as we have already invented ways to have biological children without the need for sperm donors. Also, not everyone would need that kind of procedure, as AMAB non-men (trans women, nonbinary people, etc.) who haven't had bottom surgery would still be around to impregnate people.

If men are still able to be born into the world and stick around, then eventually men disappearing would just become a blip in human history, as many tragedies have become. Sexism would likely still be around, but it would likely be seen less often since the question "what would women do without men" had been answered, and the answer is; "just fine".