that's easy... when you start putting someone else in danger of a wreck.
anytime your actions start putting someone else lives at risk. the line has been crossed.
when you put yourself in a position that if someone brakes checks you. then you immediately slam on your brakes. the vehicles in back of you has a high probability causing a very bad wreck.... a line has been crossed.
if someone is actively trying to get out of your way and/or it's not possible to get out of your way and has clearly signaled they don't want to be tailgated and yet you still are on their butt.... a line has been crossed.
your need to get thru does NOT trump someone Else's rights to get home safe.
do you know how many wrecks you personally have caused? keeping in mind every time you slam on your brakes while tailgating has a potential for causing a wreck for unsuspecting cars behind you.
notice I'm not even concerned about you getting into a wreck. because I'm assuming you've become so adept at hitting your brakes. hitting the car you are tailgating is likely not going to happen.
