Sam, is english your first language? Or are you using texting type format to talk here?
Here I searched the internet for an appology poem for cheating... I changed a few words to make it work for you. But don't for get you need to tell her happy birthday. Maybe you should first just send her a bday card just about her ... Then the next day send some thing like the below poem. Don't muddy up her bday with your stuff since her bday is about her.
Sorry for Hurting You
I know I hurt you
When I did what I did.
But still without you
I don't think I can live.
You're the only one
That I have ever loved.
You were my shoulder to lean on
When things got rough.
I know it was stupid
And a huge mistake.
Will you please forgive me?
I'll do whatever it takes.
I cried myself to sleep at night
Knowing that I shouldn't.
I should have moved on
But, well, I just couldn't.
But when I cheated
Was when I realized
Just how much you meant to me
And still now and then
The tears stream from my eyes.
It's been a while.
And I still can't move on.
I just don't want to think
That we are really done.
I was so scared to tell you
I thought that I would lose you.
I had on doubt about it
And it came true.
I thought that we could work things out
And build our trust back up.
But I think I really lost you
And to even think that is really tough.
I compare other women to you
But none comes even close.
All they want to do is
Play games and party.
You really were different
And that's what I liked.
You held me close
Made me feel real.
Even as I write this
Tears fall from my eyes.
I can't believe I did that to you
Then turned around and lied.
You were the most precious
Person in my life.
And maybe if I never did that
We'd still be doing alright.
Sorry I Cheated by Ralph Acosta