Stupid bugger almost hit me

[FordFan86]

I was pulling up to a fairly big round about, was in the right lane (2 lane road and 2 lane round about), i pulled into the left lane about 100m before i hit the roundabout and i was next to a white XF, we were side by side thru the roundabout, and just as we were exiting he started turning into my lane.
I swear if i had not hit the brakes as quick as i did he would have taken out my front 1/4 panel at about 40 k an hour :\
I honked at him after braking, he pulled into the right lane again pretty fast, i speed up, window down finger and abuse out the window... was an older male ~50-70 (can't tell when they are older :\)
then just pulled over while testing out the ABS, called my dad and just left it a few minutes before i calmed down.
He scared the ****ing shit out of me and i came quite close to just booting off at 150+k, realised my luck with coppers and fines that would not have been a very good idea so i puleld over and called dad
EDIT: he was about half a car length in front of me, the roundabouts a sort of curvy one when it comes to and end so he would've hit me at an angle as i was still in a fairly straight line