Having a hard time with someone who thinks they know it all in a negotiation try this negotiation st 

Your energy shows me everything...You must be very smart!

her: “I know you’re a veteran in this industry. What do you think is fair?” me: “no u”

I owned a real estate company for 35 years and taught these techniques, among many others, to my agents all the time. The problem is/was that very few have the personality and drive to use what they've been taught. Some used some of the techniques, while failing to use others. I had one great agent who would make the sale, and then, instead of shutting up, continue to talk until the buyer had doubts! The "silent close" is often the most powerful!

As a former car salesman I can say that negotiations is an art. Dang I was so good at it.

Honestly, of the 6 houses I've bought & sold throughout my life, I, Joe Customer, had to do the hardline negotiating because my female realtors were WEAK-ASS negotiators. They'd try to come off as boss-biatches and then fold. They were great at identifying what I was looking for and at managing the process & the paperwork, but the weakest negotiators I have ever met which used to piss me off when having to pay that fricken 6% fee. Yes, I was in sales, but was a professionally trained sales person selling enterprise software solutions but you would have thought they would be too.