Failure?

My marriage has evolved into something i can't fix. In fact, the best way i can describe it is, i am married to my favourite flatmate. One who pays all the bills.
He doesn't want to invest in the kids.
He doesn't want to participate in family activities
He is not interested in a physical relationship with me.

I'm on my own. I'm living a single parent life. Our children have issues that he has no idea about [IE: Our daughter has become lactose intolerant]
I'm living my own life with my own freinds that he wants nothing to do with.
He is quite content to sleep on the far side of the bed, Do his own thing, in his own little world, and not make any effort for something more, because he desires nothing more.
Like he just wants a wife to be there for the basics, minus sex.
He doesn't even acknowledge 'our ' song anymore!

Meanwhile, sexually, i'm a ticking time bomb! I have a very active libido. He knows that too. Sometimes i feel like he's pushing me to look elsewhere so he can justify his disinterest further, as that is what started it. I became friendly with a guy online. It wasn't anything major, but he filled a space John wasn't filling. An emotional affair? I never met the guy. And i ended the contact. But I've been paying for it ever since - over a year later. No sex. limited affection. teasing moments that go nowhere.

I have fought to make it something different - something better. And to outsiders, we have the perfect marriage. We get along great, have a great sense of humour and banter openly together like old friends. People often comment on how cute we are together.
But the reality is: I live with a flatmate who pays the bills. I guess some people would love that! And i do in some aspects. But i signed up for a marriage. I signed up for intimacy, sexual exploration together, family decisions, Planning stuff, BBQs with friends.... Growing old in each others arms.
Well at least that's what i THOUGHT i was signing up for!

Apparently i was wrong O_O