Think twice before hitting the send button.

I received an email from one of my son's moms the other day regarding one of the
boys in their "group".  They are in 6th grade and are in the habit of hanging
out as a group sometimes after school in downtown HP.  Sometimes they go in
pairs of 2 sometimes not, this time it was about 5 or 6 boys.  One of the boys
left his cell phone at home and asked all of the boys if he could borrow their's
to make a call.  He is a sensitive but good kid and started to cry when no one
offered it up right away.  Eventually they all said he could use one of theirs
but by then I believe the damage had already been done.  He said no and left and
ultimately started to walk home in the cold rain on Wednesday of this week. 
Luckily the mom who sent the email was driving and noticed him walking alone and
crying.  She stopped, picked him up and drove him home.  The email was sent
shortly thereafter.  I was so sad and cringed at the thought of "what if it were
my son".  I was quick to voice my opinion, shame on me.
That night as my son had a basketball game and was suprised that two of the
mom's seemed pretty annoyed at the whole thing and didn't think their kids did
anything wrong.  After the game I talked with my son and shared my
disappointment.  I explained that I expected him to do the right thing and stick
up for his friend but he didn't.  I also explained that he can't have it both
ways by going over to this friends house all of the time and then not be there
when his friend really needed him.  It was a brief conversation that night that
was continued the next day along with my ex-husband.  We are concerned.  The
next step is what is hauting me.....I took it upon myself to send an email to
the "moms" and instead of writing in a warm and fuzzy tone, I sounded downright
condescending and self-righteous.  Hence the downside of communicating via
email.  The replies, texts and voicemails were horrible and gave me the wake up
call I guess I needed to stay out of it.  I since have apo
logized for creating such a mess and have asked for forgiveness, I have
received one reply.  I expressed to all of them that I know we all parent
differently and that my main concern regarding this situation was the "bullying"
aspect of what had happened.  I was also asking for their help so we can talk as
a group to work on remedying the situation.  I know that won't happen now and I
am okay with that but do I have a morale obligation here to anyone other than my
son?  He has reached out to his friend to apologize and I have let it go and have moved on.