Ok van driver did cut you up, but in all fairness they were ahead before you sped up, probably in their blindspot. Looks like a merge in turn so being ahead did actually give them the right of way.
Simply easing off would have averted this. Cammer is a fool.
Mate, you're driving miss daisy, then boot it when the van wants to get past. Play it back, see for yourself. You do not EVER speed up while another vehicle overtakes
He is good driver