Consider this: if you don't believe there are two, and only two sexes and genders (cissexism), you can't really uphold heterosexism ('cos once you go down the slippery slope of more than two, what's stopping you from seeing everyone as a different sex and gender? Nothing, that's what). And why would you, indeed, see any necessary complementarity in masculine and feminine? And if you don't believe masculinities are inherently better and more valuable than feminities, or some other -inities, what'd be the point of dissing any people not on either spectrum, or people rejecting their assigned sexes and genders?
It all holds together. Sexism comes with cissexism which comes with heterosexism - they're a nice, evil compact bundle, full of misery for everyone.
They can't be teased apart, either. You can't pick a nice dose of transphobia to go with opposing sexism, or heterosexism - if you want to oppose sexism, it's just not on to diss trans women for being feminine. If you want to oppose heterosexism, why would you exclude trans-cis homo couples? And if you're against cissexism, it's no good to be homophobic: how could you defend people's rights to ditch their assigned sexes and genders as they like, and then require them to conform to hetero-only relations? As if you could define hetero-only to exclude anyone without bringing in cissexism!
Other than that tidbit, I'm rather down and out - turns out my childhood was not quite as bad as I thought it was - it was considerably worse. Hello, therapy (no, it's not about teh trans, for a change). This time, I really actually need therapy, and seems like I can benefit from it, too.