I wrote this a while ago. It relates to an ex who got involved with her own brother. But because of the act I found real happiness

Remember the time you came to mine?
We laughed and cheered, it was a sign
A sign of our love for each other
Then you went and shagged your brother

Seriously, what up with that?
It's just wrong plus he was a twat.
In my angered state
With my love gone and replaced with hate
I phoned the cops and shopped you in
Serves you right, for that sick sin

But now I'm over you and that sick act
For I have found new love and that's a fact
As strange as it sounds I must thank you
Cos without your incestuous affair with your sibling Stu
I'd never have met my real true love
So have fun, having sex with your bruv