Your felt your idea wasn't taken seriously in a discussion? You felt you unintentionally became defensive and awkward in some social situations?
Congratulations, you just experienced some of the most universal feelings being a woman in our current society.
This talk about "can't I flirt anymore?" and similar is just sad. Boohoo, of course you can flirt, but being socially awkward/stupid while doing it is what you can't. That means growing a social competence and empathy in general, then men wouldn't end up in these situations.
> How should we act in an era when one mistake will haunt us forever?
Stop feeling sorry for yourself and thinking just being a "nice guy" is enough, that you're somehow done when it comes to equality. You articulate some of my own thoughts so this is just as much self-critique. I struggle with this everyday. I think those feelings arise when shifting of power arises, we feel something has changed and changes often lead to confusion/defiance, even though it's a change for the better. A recipe for how to act is also terrible, it's not like there is a check list of things to do and then everything is ok, it's a complete transformation of your mindset (and some of our culture) and that realization is quite overwhelming. But if I had to give some suggestions I'd say start listening and take women seriously (first, understand what taking someone seriously means..)