A mother's heartache

Dear mothers of boys...
I'm only singling you out because I don't yet know what it's like to have a girl.  I guess I, myself am a girl, but my whole life I've been surrounded by brothers, boy cousins, and now little boys.  I've always felt protective of my brothers.  I know now that they were much stronger than I thought at the time, but I wanted nothing to hurt them.  I couldn't stand to see them cry.
So I'm speaking to you - mothers of boys.
I'll tell you this much.  I have discovered the single most painful event I've had to endure in this tiny little life of mine as a parent.  I have found the one thing that will make even the strongest woman crumble into a heap on the floor.
I have watched my little boy try not to cry.
He's way too young for that...that's what you're thinking right? Me too.
Yesterday Liam touched my curling iron and it was hot.  Right away he pulled his hand back and kept trying to talk to me about things that were unrelated, all the time holding back the tears that he wanted to let go of at that moment.  I told him to cry.  I begged him to cry... let it out little one.  But he held ever tear back.
I ask you, experienced mothers, have you ever seen anything as willing to break your bursting heart than a little boy - your little boy - trying so hard to be strong.  Willing himself not to cry?
For centuries mothers have had to go through this.  How do they do it? 
I'll tell you this.
I haven't been properly prepared for my heart to break so often and so willingly.
THIS they do not tell you in all of the adoption and birthing classes that you sign up for, expecting to already know it all.
THIS is not in the parenting books.
THIS is not on Super Nanny.
THIS feeling, although terrifying...is also what reminds me that I have an opportunity to love these boys so fiercely. 
It all comes back to love.