Living in a failed marriage (w/ kids)

How do you manage a failed marriage? Married 13 odd years, 2 kids (10yo boy, 7yo girl). No sex or intimacy for over a year or more. In past when it did happen on rare occasions, it wasn't worth the wait. Worse part is her micro focus on anything negative I do or don't do. Example: I could take kids out to park for 1-2 hours after work 4 days in a row, but she will remind how I didn't do it on 5th day. It's hard to mend a marriage when there's only one person interested in doing so. She complains about fatigue, but has endless energy to complain. I describe our relationship as a "Platonic Parenting Partnership". Feel trapped due to kids, plus we own a duplex 3 ways with my brother who lives upstairs. Starting over is not appealing either because I feel I would end up with another divorcee with kids of her own, and that only plays out well on sitcoms. This negative relationship has eroded my happiness slowly to the point of being numb and ambivalent. I feel like an asexual man who's only heterosexually curious... I have never cheated on her, only went to some strip clubs with the boys. ; Caveat is this is only my side (there's always multiple interpretations to each situation). I know childbirth changes some women drastically. My wife had a tougher childhood than I. Her dad left when she was 3, and they never reconciled. Whereas my parents divorced when I was 17 and I didn't really care. She has had medical issues, which has papered over some of the problems, but as I told our marriage counsellor a couple of years back: "I have empathy fatigue".