I'm sorry to hear that it's not working out Tavs.
Be honest with her and tell her face to face, tell her the reasons and that you regret that it has to be this way. Afterwards do no contact thing so she can get unattached.
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~