1st accident

So the other day I was coming from shopping with my boyfriend, we we're on the way home when BOOM we got into an accident. The person in front of me stopped short causing me to stop and when I looked in my rear view mirror all I could see was this silver car coming towards us and before I could even breath "bam" hit us then I heard another bang and we got hit again, apparently a truck hit the car that hit us causing it to hit us again, all I could do was cry. I didn't know what to do, how to react I honestly wanted to get out and bash all of their faces in and cuss them out but my boyfriend just kept telling me I need to calm down, everything's okay. luckily it wasn't much damage done to my car despite how hard we got hit, the bumper is hanging my trunk is jammed and my back door won't close all the way, but I still have my life so i'm grateful. Now whenever I drive i'm paranoid I think everyone that gets behind me is going to hit me, I keep picturing the crash in my head. I feel bad because the person responsible for the accident that was in front of me got to drive off as if nothing happened and the driver of the truck that hit the person behind me was held responsible and has to pay which isn't right but....someone had to take the blame, All I know is I defiantly don't ever want to be involved in another accident especially not with me being the driver.