Are you asking for a permission to break a relationship that does not serve you, a relationship build on a lure of illusion?

I sort of understand. 11 years knowing someone, and it's not really all that bad, just not quite good enough either. It is much easier when there is anger, hatred, pain, then we know we need to go elsewhere and we feel justified.

This is how people screw up their life: they settle for eh.. i guess, I can live with it.
Yeah, sure I wanted to be a doctor but being medical office assistant pays my bills.
Yeah, sure I wanted to write a novel, but writing bits and pieces just for myself is good enough.
And so on.

The issue is that you are not true to yourself. You allowed yourself be snagged by a lie and offered your loyalty to one who did not earn it. You had a relationship with a sock puppet, while the man wearing the sock reaped the benefits. Perhaps he felt like a failure, so he told a young girl grandiose stories of himself and took a ride on the wonder in her starry eyes. Whatever.

Is it fair to end it? Dear, it was not fair from a get-go.

If you need permission, I give you my permission. Go and be bold. Live your life fully, take risks, make difficult decisions. Stand up.