I agree with others above. The time to have stopped that convo was just before the "what does that mean?"
Yes, she may have been upset beforehand but that's up to her. If you had a) not responded or b) responded briefly with - no problem - or something similar, you wouldn't have opened the door for her to have come back with what she did?
She is highly reactive - and you are not far behind her. So, really work on the 'not reacting' to her emotional bait - and merely respond to the practicalities of the situation - you want to swap the puppy? Yes that works for me. When shall we do it? Saturday at noon is good...etc...
I'm not sure how you feel about her having access to the house, but given the present dynamics, you may want to text and let her know you can't be around now, but doggy will be there, walked and waiting if she wants to swing by and grab him..
Just keep learning from the feedback and the dynamics that are happening here. If your own communication improves, that changes the dynamic....
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus