I told my mum my partner is a transman

Coup

And she took to it... Questionably? She went on this huge rant about how she doesn't think people need labels or should be put in boxes and that people should just be allowed to BE, but at the same time argued how ridiculous it is that identifying as a different gender is "trendy" right now (and she wouldn't even let me finish talking when I tried to explain that the only trend is that people are more safe than ever to come out) and went on to say, essentially, that people are on a spectrum but "shouldn't announce it to the world every time they feel different than they look".

It was really upsetting to hear, because even though she agreed to call him by male pronouns, she obviously doesn't believe he's actually a man, and subsequently, she would never be accepting of it if I came out to her as nonbinary.

I did not expect her to react like this. She's always been accepting of my sexuality (if a little forceful on getting me to choose something other than queer like bi or lesbian), and seemed like she genuinely wanted to understand the plights of LGBTQ+ people, but she just got so angry about the subject of non-cis genders and pronouns....

Does anyone have advice on how I can support my boyfriend and protect both of us from transphobic behaviour and language while also keeping the peace???