@Retarded Rabbit
I accept that a good chunk of people here will disagree with me, but this doesn't sound like some irreconcilable, imminent descent into castration and trespassing into women's bathrooms. People here, myself included somewhat, are hypersensitive to troonshit, because we're already predisposed against it, but they really are a vocal minority.
It's incredibly difficult to assume the worst about people you consider friends, so if your boyfriend, in his capacity as a nerdy internet type, is being assaulted with troon propaganda by ostensible friends, friends who have never actually done anything to give him a bad feeling, it's really not surprising that he'd accept many of their claims in good faith.
You've pointed out many tiny things that all point, to me, to this guy not being a lost cause. He knows you use KF, and tolerates it. He doesn't like it, but he tolerates it. That's already huge, and extremely out-of-character for a tranny. And he listened when you gave examples of the negative effects of their mutilation surgeries instead of just calling you a Nazi, that's another giant "Not a closet tranny" flag. And further still, he had a sensible, human reaction to that creepy-ass "egg" thing being directed at him.
Nothing you've said about him, to me, describes some soon-to-be genetic dead end who somehow sees an anime girl when he looks into the mirror. He sounds like a pretty typical center-left nerd guy who doesn't want to rock the boat or believe the worst about his supposed friends. Cutting him off and running for the hills right now is silly. Instead of throwing a bunch of ultimatums at him that he must believe to keep you, why not just try to calmly prune some of the really malign influences? Nothing as aggressive as "I DEMAND YOU LEAVE THE NEW VEGAS IS PEAK TRANNY FICTION DISCORD SERVER RIGHT NOW" since that's going to come off as an attack, but start small. "Those guys calling you an 'egg', I'm sorry, but that's fucking creepy."
Show him some articles from detransitioners, unbiased medical reports on the harm of the drugs, normal stuff like that. Try to make it clear that you're not coming from a place of "phobia", and instead you have very genuine concerns about this stuff and the harm it can cause.
If you otherwise really like this guy, and you get along great, it just seems like it'd be a source of endless regret to totally cut ties because of something as ephemeral as: "Well, maybe in several years, we'll have kids! And then, many more years after that, what if the kid wants to be a tranny?! Can I trust him not to enable it?!"
Besides, if you're worried about a hypothetical kid trooning out, here's how to avoid it: Keep them off fucking social media. Don't give them full-trust unregulated online access 24/7. No public school system.