Hello....
To the thread poster, I think u shouldn't talk to ur boss about ur
problems with her. Esp since u are new, just 3 months. Ur boss will
think u have adjustment problem/ not well received by current
staff.
When she knows about it, and even when ur boss really, say, take
actions, for example by talking to her and u, have a meeting with
the 2 of u, etc, I think she will seriously hate u, and so this
will be counter-productive.
I agree that u should try to let her guards down. I think since u r
new, she doesn't really know u. She might even think u r a threat,
make her look less relevant.
For now, just respond professionally. And try to get to know her
better. As time pass, the 2 of u need not be enemies. You need not
suck up/ behave like a hypocrite, but u need not take her as an
enemy too. As time pass, she might change her attitude too. This
will be more productive, and the way to go.