Cutting out their tongue eh? How medieval of you.
No, no, nothing like. They'd still be able to write and pantomime and whatnot, after all. Just... say something like a geas became an actual thing, and they got hit with one preventing communication. Most people, even some of which have pretty odious views to me, I'd be bothered by it to some degree. WBC, not so much.
And yeah Helg, being able to talk about something like that, and talking about it more, generally
is a good sign and a healthy thing. Probably not always, but usually. Other than that, my best advice would... probably be to do some research? It's been years since I last time I brushed up on generally recommended best practices for interacting with abuse victims, but I'm pretty sure there's quite a lot of material available; just in general, and also specifically from abuse support groups and counseling organizations and whatnot. Which... yeah. Possibly consider asking a psychologist (particularly if there's one you know and trust), or an abuse victim support group or somethin'.* They often accept some kind of request for anonymity, particularly for things from long past or that the victim has no intent of seeking legal redress for.
In the meantime, probably don't let it effect you too terribly much, particularly if it's no longer traumatic to the victim. I
am pretty aware that a lot of abuse victims (sexual or otherwise) are not exactly appreciative of people significantly changing their behavior after learning about it; regardless of what happened in the past, they're still the same person, etc., etc. Maybe a thanks for the sign of trust, offer of support or whatnot if and how they want it, that sort of thing, but otherwise just kinda' be the friend you've previously been. That'll most likely help more than just about anything you can do, really.
*Maybe even ask your friend if
they've been in communication with something like that, and ask 'em if it'd be alright if you talk with who/what ever that happens to be, too. Could be a good idea regardless just to have a second person aware of whatever they're dealing with that way. Can help make sure they're not being taken advantage of or somethin'. Doesn't sound like it's likely they are if there's any being consulted, from what little you've said, but it's always a possibility.