Hwy 99, Madill Oklahoma toward Hwy 377 toward Texas state line

In December of 1982 right after Christmas, I was traveling in my car with my cousin in her car behind me. It was about 2:00AM. We left Tishomingo, Oklahoma and went thru Madill, Oklahoma toward Hwy 377 in Texas to go home from visiting family for the holidays.
We had left Madill and were on Hwy 99 just west of Madill.  The road has very low rises, gentle slopes it is not flat.  I was the lead car. What I saw ahead of me on Hwy 99 was a huge reddish orange fireball which made me think there was a bad accident ahead.  My perception was as I topped the little slope I could see the fireball, then as I went down the lower part of the road it could not be seen.  This went on for about 5 miles.
At one point, realizing I was driving erratically, I pulled over to explain to my cousin to be careful, as I did not want us to drive into an ongoing accident scene.  She said she could not see anything unusual whatsoever.  It was unnerving to know it was just me seeing this.  This light completely covered the width of the road and was about the size of the sun at sunset, yet my cousin could not see it.
I kept on driving slow (thinking I need to be prepared to stop) and never ever came up on the accident.  Finally the light was not seen any more, we had crossed the bridge into Texas.  
To this day, we talk about that strange night and she still declares that although she believes me that I saw something, she never saw anything.