It sounds like everyone is experiencing a great degree of pain. I"m sure the mother of the boy who killed the cyclist is feeling helpless and angry too. I copied the following from a website.

There is no right or wrong way to grieve. All your feelings are normal. It is helpful, however, to know
that human grief is a process that often follows a healing pattern.

Shock is the first stage. It is accompanied by disbelief and numbness.

Denial follows quickly, crying "I don't believe it," or "It can't be."

Bargaining is your promise that "I'll be so very good that maybe I can wake up and find that it isn't so.
I'll do all the right things if only...."

Guilt is painful and hard to deal with. This is when one says over and over, "If only I had..." or "If only
I had not..." This is a normal feeling and ultimately it may be solved by stating, "I'm a human being and
I gave the best and worst of me to my friend (child, husband, etc...) and what he or she does with that is
his or her responsibility.

Anger is another big factor which seems to be necessary in order to face the reality of life and then to
get beyond it. We must all heal in our own ways. Anger is a natural stage through which we must pass.
Your anger at your deceased loved one may even make you feel guilty, or it may be because your own
life continues whereas your friend's life is over.

Depression is a stage of grief that comes and goes. Knowing this, be prepared to give yourself time to
heal. Resignation is a late stage. It comes when finally you accept the truth.

Acceptance and hope! Understand that you will never be the same but your life can go on to find
meaning and purpose.