Cardiff, Wales, UK
I like this, it brings out both the confusion and despair of a very personal situation. I would hope it's not a personal memory, but suspect it is. It is all too common and sad, but as you last stanza suggests, people can move on.
Having said that, if I may a couple of points on the poem itself rather than the feelings behind it. You have gone for a very rhythmic form, but you lose it on occasion. This can be done for effect, but it doesn't seem to work here.
"Too much water under the bridge
We cannot contain the deluge
Youíve just lost all of us,
You didnít think you had anything to lose."
Might I suggest the last line works better as
"You thought you had nothing to lose"
"I gave you all that I had to give
But it just wasnít enough.
I never thought I had the strength to leave.
But I know I can be tough"
The third line fits better as
"I thought I'd lost the strength to leave"
It's a shame to nit pick like this in such a personal work, but I did find the break in rhythm distracting.
Hope you don't mind the comments, nice poem