Don't be so cockey! You will get yourself in a lot of trouble that way.
You are correct to insist upon not meeting on Chang's terms and turf. Make her come outside her lair. But Union Square is now compromised. If she is a worthy adversary in any way then she has already considered the possibility you will insist upon the Square and will have some of her own goon squad standing by there. You need to select another very public place where you can meet and disappear when necessary. Choose now, but do not discuss it here -- just in case someone on their side is lurking and monitoring our conversations.
Make Chang appear on your terms on your turf. And don't forget this is FOR REAL. You do not get "additional lives" to use like in a video game. Here, you die and its over. Being careful is your only chance.
Koala, Captain, Team Andrew