Charlyn Willis got engaged last Thursday and now the whole world is in on the big news. You see, the Savannah, Ga., native was so excited after receiving her new cushion-cut diamond engagement ring from beau, Dennis, that she took a selfie while sitting in her car and hastily texted the pic to her sister — or that's what she thought she was doing.

Willis had typed in the wrong number, but through a fortunate stroke of serendipity, accidentally shared the ring pic with Buffy The Vampire Slayer star Sarah Michelle Gellar.

The '90s icon, who has been married to Freddie Prinze Jr. for 15 years, shared the bride-to-be's selfie on Instagram and Facebook, writing, "This is #CharlynWillis. She got engaged yesterday, and meant to text her sister, but in all the excitement, got me instead. Her sister didn’t respond, but I did. So please help me say congrats, to Charlyn. (And her fiancé whose name I don’t know) #congratulations.”

Well wishes came pouring in and Willis was quick to respond with a heartfelt thank you and a pledge to invite Gellar and her family to the wedding.

"Omg! Thank you Sarah! His name is Dennis! Thank you so much for this," Willis wrote. "You’ve truly made my engagement experience even more of a life changer! Please know when we set a date, I’ll be reaching out to invite you, Freddie, and the kids!"

Later, the 28-year-old Willis wrote, "I guess the best way to announce your engagement is to have a celebrity to do it for you. THANKS Sarah Michelle Gellar… AND YES, I SAID YES to Dee!!!!!”

Willis' story has been picked up by The Knot, Bride's, Glamour and The Daily Mail, among other high-profile outlets. Willis wondered out loud on Facebook whether any of them would cover the wedding.

Gellar's Facebook post — which currently has 12,481 Likes and 143 Shares — generated a wave of congratulatory messages for Willis and sweet compliments for the actress.

"Many blessings for a happy marriage!" wrote Facebook user Laura Engel. "...and Sarah Michelle Gellar, how amazingly sweet are you to not only respond to a wrong number, but to spread the joy!"

"And this is why I have always been a huge fan of yours," added Judy Anne Crosby. "Such a kind, generous, and thoughtful woman you are. Congrats to this beautiful woman and thanks to you for always being genuine."

Credits: Selfie images via Facebook/charlyn.willis, Facebook/sarahmichellegellar; Sarah Michelle Gellar photo by Rach [CC BY 2.0], via Wikimedia Commons.