He is suffering in so many ways: guilt; the horror of what he has done; the realisation that he could have prevented it; the fact that he will now face serious punishment for his actions.
In the meantime, the families of two people are going through their own purgatory, having lost two people unnecessarily. Two lives lost will affect the lives of many others.
All because, while it's not okay to read a book, magazine or newspaper while driving, it's considered perfectly acceptable to use a mobile phone.
People have died or killed others while distracted, and that distraction is often sending or receiving a message on a phone. The bus driver was arrested after CCTV in the bus showed him on his phone when he hit those people. Without video recordings to prove it, how many other crashes are the result of digital stupidity?
How many phone conversations are cut short because the driver suddenly needed two hands and all his/her senses and found them lacking?
How many people sent their final words via Messenger?
How many more will do so before we realise that mobile phone use is absolutely fine if you're in a car - as long as you're not the driver?