So I was driving to the airport this morning for work and was on 635. I was getting off at an exit to try and get around a wreck when a guy in a tahoe came flying up the shoulder of the road. When he realized that I was getting onto the exit he decided to drive around me on the grass shoulder with out slowing down and ended up spinning out and almost crashing. After he got his car stopped he got out and proceeded to beat on my window. I could not drive away due to the traffic, thankfully nothing happened but had the window broken I was prepared to shoot him. It is the most scared I think I have ever been. Is there any advice yall have on  things that could have been done better?

Called 911.
DPS loves those that pull off onto the grass like that.

As a fellow DFW'er I can sympathize.  635 is a nut house all to itself.  

I have a dash cam that also records audio, I find that very comforting for road rage situations.  There's no he said/she said.  "Here's the video, officer."

Seems like you handled it well.  In Texas our car is an extension of our house.  Had he broken my window or tried to open the door I'd have shot him.  The only thing I'd have done different is call 911.  Not that anything may have come of it but I prefer to get that stuff on record.  

I've called in incidents like that before even though I thought it was over.  Then the person tried following me home, so I called them back and said "Hi I just called about (insert here) they're now following me.  I've made 4 right hand turns and they're still with me."  Then if it escalates later I've already got calls on file trying to resolve it peacefully.

You did fine, OP.  Glad you didn't have to shoot him.  Got Texas Law Shield?