My name is norimasa yamagishi and living in Australia due to delegation by
my company.
I am very sorry to send English message, because I just started the
Internet.
I cannot to type Japanese. I think your sadness and vexing is bigger than
mountain and deeper than sea.
I saw the photo of your son,lovely and I feel how much your sadness.
The family who lost the member has the long long time to heal its sadness.
I lost my youngest brother by traffic accident. 
I am sorry but I think you and your husband  must live strongly and always
keep the memory of your son.
Your son brought the happiness to you for 15 years and he was very happy to
be born as your son.
I am sorry again to send  my sympathy by English. 
Best regards.