How to get rid of hate? I have a friend that I met few years back. He always look polite, look decent, and look helping others a lot. I did him a lot of helps that no friend would do to him. Later, when I needed helps he really, replied me with very bad words, which I never thought he can even talk like that. This thing really becoming something that I cannot forget. It seems I suffer it a lot. I was thinking how to get rid of this for a long time now. What are the practical measures in Buddhism to get rid of such hate inside one's inside. Thank you.
There is a solution given in Buddhism for the exact matter.

I think you may have heard about the meditation called "Maithree / Meththa" (Metta). There is a certain variation of that to prevent such hate.

So the solution is simple: do this meditation, specially targeting this person and the memory that you are trying to get rid of.



After doing it for about 10 minutes move to the following way of focusing without stopping your meditation.
The next step is to focus on bad effects of anger and hate:


How it effect badly to the path
How it gives you births in lower realms (like among animals)
How it will ruin your appearance in next lives
How it could reverse you accomplishments in meditation
How you will not be able to reach jaanas (Also known as Dyana)
And so on....


You should also add these:


How that person's anger and bad words would affect badly to his path
How it could give him births in lower realms (like among animals)
How it will ruin his appearance in next lives
How it could reverse his accomplishments in meditation
How his will not be able to reach jaanas (Also known as Dyana)


This is done to get your mind to feel sorry for him and pity him.

(The very second your mind comes to this phase it will no longer have anger for the incident or the person that made you angry).



Now you should focus on how your thought are generated and how they were generated in that moment.
Try to recite these with your mind:


What I hear does not contain anger or hate: I make it in my own mind
If I hear something i like i start to like it,and i start to like
that person who said it
If I hear something i do not like i start to hate it,and i start to
hate that person who said it
So this hate and love is also a product of my thoughts, nothing in the
world ever made me love or hate anything.
So like this every feeling I have is a bundle of thoughts,mind's
creations
Everything that made me happy and sad has always been a thought in my
mind
But without seeing this I was foolishly blaming others for my anger
There is a functioning body and a thinking mind
I looked everywhere there was no "Me", only thoughts
But I thought there is someone called "Me"
It was this mind that made this reality and all the feelings I have
felt
I am not the only one who is fooled by this, everyone is!
If there is no "Me", then there is no "Him" or "Her"
Only bodies and minds that made them work
It is foolish to have a grudge with anyone 
I give up this anger, there is no point carrying this foolish burden.


I guarantee you in one sitting you will be a different person. This
   would take about 15 minutes. If that is too long do the two parts
   separately (don't leave too much time in the middle). I have done this
   and it is instant in giving results.