The man accused of kidnapping Jayme Closs and murdering her parents wrote in a new jailhouse letter he “can’t believe” what he did and plans to plead guilty.

Jake Patterson, 21, wrote to a KARE-TV reporter saying he has “huge amounts” of remorse or regret for what he did, and will own up to the murder and kidnapping charges at his March 27 arraignment.

Patterson said he doesn’t want the 13-year-old girl’s family “to worry about a trial.”

“I can’t believe I did this,” he wrote.

A photo of the letter, sent in response to a list of questions from the reporter, has “I’m Sorry Jayme!” written in big balloon letters.

A scribbled sentence reads: “For everything. I know it doesn’t mean much.”

Asked what led him to kidnap Jayme in the first place, Patterson wrote only: “It’s not black and white.”

Prosecutors say the former cheese factory worker spotted the girl getting off a school bus near her home and decided he was going to take her.

But Patterson claimed authorities were “twisting [his] words around.”

“The cops say I planned this thoroughly, and that I said that … straight up lie. This was mostly on impulse,” he wrote. “I don’t think like a serial killer.”

He continued: “At the time I was really pissed. I didn’t ‘want’ to. The reason I did this is complicated.”

Jayme was allegedly held captive for 88 days inside Patterson’s cabin in the remote town of Gordon, Wis., before she escaped in early January.

Patterson writes in the letter that no one knew about his sick scheme and that he didn’t leave any hints about what he was up to, forcing Jayme to hide when his father would come visit the cabin on Saturdays.

When asked what his long-term plans were if Jayme hadn’t escaped, Patterson only wrote: “Won’t say. It was really stupid looking back.”