Yeh she might be mad, but it doesn't mean you're a horrible jerk for saying it. You were sad and it slipped out, happens to everyone sometimse. I'd be surprised if she holds it against you for any lengthy period of time. Maybe, give her some chocolates and take her out to see something funny.
There's a great art of making it up to people. Exercise it.
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~