The issue is your ex-girlfriend's. Why did she feel upset? I don't know; perhaps she was transferring some of the feelings of rejection or frustration from the cancellation onto the current situation. That would be understandable, but not reasonable. What are you supposed to do, present all your potential dates to her for approval? She's your EX.
IMO, you don't owe your friend anything in this situation, but you may wish to talk it out with her and help her work through her issue. Some communication between her and the other lady might be really good for your friend, to help sort things out and clear the air.
In the future, you might want to spend less time talking about your love life with this friend.