I don't think Steve meant to say that out loud.

Cheryl is a sore spot... seriously tender. Turner told anyone who knew Steve and Tom that they'd both been killed in their accident. Cheryl couldn't handle the thought (They were engaged to be married about a month after the accident happened.). Unable to cope she found Steve's service revolver and killed herself.

One of Steve's mental fractures led to Cheryl speaking to him as his conscience. He was never sure whether she was a figment of his fractured mind or a ghost who haunted him. Either way, she kept him out of some more serious shit when his life took a turn towards the darkness.

Maribel's introduction to his life actually led to Cheryl's final "excorcism" (or her releasing him. Whichever way you want to think about it.).

Still, he loved Cheryl very much and was devastated by her suicide.

Want the intimate details? I highly suggest In the Beginning to scratch that curiosity itch. Talks all about the aftermath of the accident and what led Tom and Steve down the paths they currently walk.