Automatic Transmission Control Module problems of the 2013 Nissan Maxima

I was traveling from houston, TX to dallas, TX midday on may 1, 2021. I was approximately 40 miles outside of dallas on I-45 traveling 75 mph when I suddenly felt a sputter and then the speed instantly decreased from 75 mph to 20 mph on a busy major interstate. I was almost hit twice as I tried to exit the interstate with cars traveling upwards of 75+ mph, blowing and honing and cursing me. I made it off the interstate and turned the car off. After making several calls for help, I was instructed by a mechanic to wait a few minutes and restart the car and try to accelerate while on the feeder. So I did, and the car did accelerate enough to get back on the interstate. I had to do this 5 times to get the remainder of the 40 miles to m destination. I took my car to metro dallas Nissan in flower mound, TX on may 3, 2021. I was told the inspection found codes p1778, p0778 found in ecm and tcm found transmission to be slipping and therefore, the cvt assembly needed to be replaced. . . . . = $5523. 00!!!! I have always had my car serviced at Nissan dealerships, maintained the car impeccably, driven with care and I am devastated! although the car is 8 years old with 139k miles, there is no logical reason for the transmission to need replacing except for defective equipment from Nissan. I plan to continue to pursue the matter. I cannot afford to spend $5k on a car I worked so hard to pay off.