Some things, such as negative influences and people who are upsetting to interact with, do in the end need to be left behind.
I don't necessarily mean that you need to cut them out of your life completely, but they may need to be compartmentalized or kept at a distance. I've had to do the same with my own mother. It's not what I want but it's necessary. It's not even because of the trans issue but because she's always been a difficult (violent and alcoholic) person to exist with. Just a fact of life with some people that you have to go your own way from them.
And I agree - what's the point of living a lie? If you're going to live at all in this difficult life, you might as well be yourself in it.