If I am hit from behind going under the speed limit say i am

If I am hit from behind going under the speed limit say i am going 5 MPH in a 50MPH. I did have my hazard lights on. Am I at fault for going slow i.e. under the speed limit? It was a four two lane road, two one way and two another way. There was a ramp/shoulder for me to pull off on but I decided to keep going. I knew my car wasn't functioning before I even got on the higher speed road. Am I now liable in anyway?