What is true love ?

Not sure what category this one should be under ,and I am not one to write about love that often as love in my life as only hurt.

What is true love ? ,is there really such a thing ?.
When you truely love someone ,happiness is what it should bring.
I have loved in the past ,and all it brought was pain.
Leaving me scared to love ,and not wanting to get hurt again.
My first love was taken from this life ,at the time we were not together.
In the time we were he cheated on me ,I always thought I'd be with him forever.
The strength to move on I did find ,and went on to meet my second love.
With him I had my first child ,but he left said he didn't love me enough.
Left alone to raise my child ,not wanting to ever love again.
The love for my child was like no other ,staying single meant no more pain.
Being a mum was so rewarding ,anohter child I did long for.
Security and stability is all I wanted ,and a little family to adore.
Along came my present partner ,wanting to take care of me.
He loves me with all his heart ,but me loving him will never be.
The situation as worked for us ,as we've been together 12 years.
But recently love as set my heart alight ,it's for another so its only brought tears.
It's why i ask what is true love ? ,and is there really such a thing ?.
Because when you find that kind of love ,surely only happiness it should bring ?.