i am just curious - how was she "attacking" you in the past that made you
feel embarassed?
it's important to understand everything have to be done within professional
boundary. personal attack is never good, regardless of who started it first.
if she is just asking questions wrt your work, and provided it's related to
the overall business objective - she's well within her rights to do so. That
's all fair game. At the same time, you are well within your rights to do
the same as well. And frankly as a manager i want everyone to do that (
tastefully). So spend some time to understand what she's doing and see if
you can poke holes in it - but you need to do it in a way that's "
professional" - such as "i want to make sure that your piece integrate
flawlessly with my piece, could you help me understand what happens if abc .
.."
sometimes though, it's not really the case that someone's picking on you; it
's just that from their unique perspective and without an understanding of
your work completely, it's very common for people to have questions. then
the onus is on you to explain. to me, that ability to articulate concisely
and rationally is much more important than the technical aspects of work
sometimes, b/c many times it will require you to put yourself in someone
else's shoes and see it from their angle first, understand their concern,
and then explain in a way that makes sense to them.
like you said, be confident, but also non-defensive, and always use business
justification to defend yourself (i.e. latest market data suggests we do
xyz, or we are adopting the same process as group abc.)