About an hour ago, I was driving home with my gf, then a guy out of the blue gets into the road and stops right there, I almost crashed with him, it could have been a serious accident so...

I got quite angry, so I started to follow him really really close, the other driver notices and we start running until a red light stops us, I stop by his side, lower my window and tell him to fuck off, that he is an asshole, he should't be driving like that, he was 35 or 40, had a son in is ~18.

It was a pretty tense moment and at the moment I didn't want to just let it go, whole thing lasted for less than 5 mins but it was draining and my gf told me the that she got very mad at me for acting like this.

I am now realizing that I made a mistake and that I put both of us in danger by not driving carefully because I was trying to catch up with another car and even this could escalate to something much bigger.

This is not the first time that I got angry at another car for almost causing an accident, however this is the first time that I chase a car and verbally insult another driver. Also this is probably the first time my gf sees me behave this way, shouting to someone else and shouting rude words.

What is the best way to control myself when other people are making serious mistakes? How can I regain confidence with my gf after she saw me act like this?

About me: 22, low to middle class for my country, relationship with her for about a year, hope my english makes sense.

tl:dr Got road rage, first time my gf sees me act this way, neither of us liked my attitude towards the other driver.