I could kill you if I wanted to

I loved him then,
Assume the throne,
Claim my prize,
For being alone.
My fault now,
You fault then,
Living these moments,
Back again.
All that worship,
Wasted away,
For the pain,
I felt every day.
Why should I,
Be at your command?
As time slips by,
Like grains of sand.
I could kill you,
I had a blade,
To your throat,
I had it made.
Your blood would spill,
Like a cup of wine,
I am here to take,
What's rightfully mine.
Give me back,
My sanity,
For your love is made,
Out of vanity.
I saw my chance,
The rising sun,
I cut the flesh,
The deed is done.
Together we perish,
In a twisted end,
A silent goodbye,
A simple Godsend.