Lachey's new solo album, "What's Left of Me," is set for release May 9. He sings openly about divorce-driven heartbreak and angst on the title track and in songs such as "I Can't Hate You Anymore."
"It's a nasty situation," Lachey reveals in his MTV special, "Nick Lachey: What's Left of Me," set to air Saturday (12 p.m. EDT).
"It's not fun. ... So, it's not in any way vindictive or an assault on her. In a lot of ways, it's more of an assault on me."
If Simpson feels attacked, Lachey says he doesn't mean any harm: "Jessica knows I still love her."
Lachey, 32, and Simpson, 25, starred in the MTV reality show, "Newlyweds: Nick & Jessica." The singer-actress filed for divorce in December, after three years of marriage.
As a result of the breakup, the former boy band star says he's "more guarded. I can't be as open with people because I've been burned."
He says his "biggest fear is being alone" and feeling like he'll "never find that person that you're looking for, especially when you thought you had it."
Still, Lachey remains hopeful.
"Do I believe that I'll fall in love again one day? I certainly hope so. I certainly hope I'm not going to be the jerk, uncle, bachelor the rest of my life," he says. "You know, it's not what I envisioned for myself, but at the same time, when I got married, that was it for me, you know, that was my life."