A long time coming

Been with someone nearly 20 years. We have a kid. There are various reasons it hasn't always worked but regardless of everything I am not physically attracted now. I won't end it because I feel my unhappiness isn't bad enough to cause the kid to have parents that are broken up. I just feel lonely. I don't know what it feels like to really feel attracted to your partner. Sometimes I wish for a death so I don't have to be the ashole splitting us up but that is so unfair and I feel awful. They aren't a bad person. I just feel like I would be happier alone. I didn't sign up for all the extra shit that came with this relationship. 90% of if didn't even appear till we had the kid. I don't even know if there's anyone I would be attracted to. I'd just like to try it.