Yeah, every single thing that Ben told Luke about Anakin was a complete lie. He didn't meet him in the clone wars when he was a great pilot and his father didn't even know he existed.
Ben pretty much lied about everything, but the reason behind that lie wasn't and still isn't clear.
"Vader, is your father, you have a twin and he tried to strangle your mother when she tried to save him. She ended up literally dying of a broken heart because he became the emperor's pet. Oh, I struck him down and it only made him stronger ... I let him do it to me ... but I'm a ghost. Didn't work so well there."