Choc, I think you are correct in saying you're afraid you'll be validating her. But that's exactly what she needs: validation of her feelings. Her feelings ARE valid, no matter how much they don't make sense to you. There is some internal logic to why she is feeling overwhelmed. But you both must be still and listen to find out what it is.
I think you're also afraid that if you start listening to her spill her guts, she'll never stop, that y'all's (there's that word again!) world will come to a stop while she just sits and complains, AND that if you seem to agree that she is justified in feeling overwhelmed, that YOU will wind up taking on all of her stuff in addition to your stuff, and YOU will wind up overwhelmed. But, in truth, you can't predict what direction the interaction will take once you two really feel safe with each other... her to tell you how she feels, and you to listen. It could be very exciting. (Isn't this pure Schnarch?)
I believe that she just wants you to hear her expression of feelings and to validate that her feelings are okay and a perfectly understandable response to the situation she is in. There is NO risk to you in doing this. ALL you have to do is listen and extend compassion.
My experience is that after being truly heard and validated, suddenly I'm full of energy and all the things I've been putting off seem easy and doable.
Cine, I did have some counseling classes in grad school, but mostly I've just been a patient for a zillion years!