warning: an extremely long response
okay, so - the only time i think it's worth it to keep these things secret is when you see your social media as a potential way to get a job and it's your main source of income. in that situation i think keeping yourself as non controversial as possible is the best way to be. in other cases though, being true to yourself is what gives you inner peace and gains you true friendships.
the larger following you have, there's a bigger possibility that you won't actually appeal to at least half of them the moment you start voicing your opinions. that's why huge accounts get hated so quickly. it's impossible to please everyone, even if you think your views are pretty rational and morally correct, and it all gets worse when the stance you share is controversial and in the heat of the debate, no matter if you have decent amount of research to back it up. one way to avoid "your followers hopping on your ass" is to rebrand completely - make a new account and be clear on your beliefs from the day 1. this way you'll build a following you actually want to create for, and people who don't like it can avoid it easily, not get jumpscared with your "proship coming out".
when it comes to abandonment - if your friends are clear "antis" at least most of them will turn on you. some might not actually care or are freaks in disguise, it happens as well. but to those who decide to leave you based on your stance on fiction - you have to reevaluate if that friendship was valuable to begin with. i ended some friendships over this, gained new ones and the trust i had between friends who stayed strengthened. you're gonna be okay.
now, about harassment - it will always happen. it's twitter, it's hard to avoid people getting obsessively mad at you. i have been dealing with this shit for years but it becomes meaningless when you don't put your self worth into how strangers online perceive you. 99% of the threats you will get are people trying to scare you, by the way. keep your personal information private and you'll be good. you can limit negative feedback by hardcore blocking. you see people with proship dni in bio? block. you see someone who follows vocal antis? block. you see an anti proship tweet? block everyone who retweets and positively interacts. you get a bad vibe from someone? block. don't get into discussions with these people, become a wall they can't break and live your life. there will always be someone who will enjoy what you do!
also, thank u so much!! stan really is just a pathetic little guy