Transmission slipping on 2005 Chevy Impala

This is a hard way to learn this lesson, but nevertheless, you should now be aware that trans fluid (and filter) need to be changed every 3 yrs or 30k miles, whichever comes first. When this schedule is not followed, trans failure can take place any time after ~90k miles, and is pretty much of a sure thing by 125k miles.

While your experience of trans failure at 70k miles is unusual, it is likely that fluid changes at 30k and 60k could have prevented this early failure. I’m confident that you will maintain your next transmission much better!

Anyway–as was said, you need to get the car to an independent trans shop right away.
Every time that you drive the car in this condition, you are increasing the potential repair costs.