Honestly, if they don't want to even hear you out, it might be a good time to take a little break from the friendship. Because a lack of respect or willingness of the other side to listen, can turn any relationship toxic. Doesn't mean you can't hang around with folks irl, or that you should take a break - it's ultimately a choice for you to make -, you absolutely should... it's not healthy staying in one bubble all the time (that's for the extremists)...
... But consider thinking about your own rights and dignity. They shouldn't be invalidating you based on something they read off of Wikipedia. Teachers don't even allow students to use Wikipedia as a source, so, like, tf? Admittedly, I'd be so tempted to tell them to grow tf up, or open their eyes, but they aren't my friends and this would probably just burn a bridge down way too fast. So being that I assume you want to keep it, maybe don't do that.
I also don't think you should lie.
Transparency is important in a friendship. Now that they know, you'd be actively lying and not just lying by omission. In as much as they have a biased and uninformed view of things, I'm not sure they deserve to be lied to. If you can't trust them to let you go on a support site, maybe it's time to move on. Or maybe you could give them space and then talk it through. But again, that's just my take on things.
Besides, this forum isn't all about suicide. Sure, one of the perks is that we can talk - without judgment from the forum (for the most part) - about suicidal thoughts and ideas, about the sort of pains we don't talk about with others off the site. Not just because we don't trust them not to judge us, but because trauma dumping on people can seriously cause them distress too. Because they might not be able to handle it -- and that's understandable. Because we don't want to drag them down to our mentality, even if it's a valid one, because it's so hard to heal from, even with support. Because we're not here because life is full of roses, and we're just concerned for a friend, we're here because life messed with us enough for us to truly be considering ctb. That doesn't mean we 100% will, and that doesn't mean they'll 100% lose us, (it might, but it's not a certainty, I mean, some even made a turn for the better and left because of that) but maybe there are just some parts of our life we don't need to involve those irl in... and that should be okay to do.
Plus, we also got a counting topic, a recovery section, a cat topic, a fox topic, and even a gosh-darn anime topic. Anything you could think of plus a place to comfortably vent. We really aren't this depressive death cult that drives every single person to suicide. We just don't judge people for using it as an escape option.
I dunno, I feel your friends could stand to take a good long look at themselves and think whether they should trust a single Wikipedia article about a whole community of people on a site that can be accessed through Google in most places, even without using a VPN, or searching it up by the exact name. I mean "Sorrow Solutions" seems to work well enough, thanks, Tantacruel. Yeah, we got our bad apples -- but so does Twitter (I wonder, do your friends use Twitter or other social media sites? If so, tell them they should sign off, because it's a toxic breeding ground encouraging people to ctb.).
And yeah, it can be very persuasive, even a single article, especially about something as ... terminal... and divisive... as suicide. But...
... we're not necessarily pro-suicide. We're just not against it. We're not of the mentality that "everyone should commit suicide, and no one should be alive" in the same vein that pro-lifers imply that "everyone must live no matter the cost or the suffering and to die, to abort, to quit life is, like, the absolute worst thing, evah!" We seem extreme because their "normal" is on the opposite extreme. We seem weird because life and positivity at all cost has been made the new normal. We seem wrong, because every individual wants to view themselves as the ones in the right, and some happen to hang onto that more stubbornly than others. Plus, we also seem to make up a minority, so that doesn't help.