What do I say to this message?

[KelHATESorangesoda]

"Hey, yeah same here Thank you! Thank you, yes I am doing good, how are you?"

That sounds crap but its what I say and would say. Just be sweet with her. Oh it's your aunt! Well it's fine then I thought you were scared because it was a random person. Just say as I said. and it'll be fine just act how you would with anybody.
Theres a guy on FB I talk to all the time and he messages me every day with the same how are you? it's just an icebreaker
Good luck