It's very sad and hurting the words your ex uttered to you. But, you have to forgive him for your benefit. You might tell yourself you'll not forgive him because he doesn't deserve it. However, not forgiving him won't affect him in any way.
You'll be the only one who is hurting. The anger, the hatred will take control of your life. They will affect you negatively both psychologically and physically. It will negatively impact your relationship with other people and when you engage in a relationship.
You will develop depression and low self-esteem. The anger and hatred will take control of your mind to the extent you will do something you'll regret later.
To avoid all these negative effects which won't affect your ex bit you; you'll have to forgive him. You cry, promising yourself you won't forgive him. But, you're only hurting yourself.
When you let anger and hatred take control of you, you are letting your ex control your mind. You've to stop it as hard as it is. You've to regain peace of mind and heart, your self-esteem and control of your life.
Tell yourself you've forgiven him. You won't hold a grudge against him and will try to forget how he hurt you. You'll find your feet to move on because the far you've come, you won't let anyone destroy it because he has hurt you.
Look back the far you've come. Don't let the anger and hatred impede your progress in life. You've to stop minding him.
When you've forgiven him, send him a text and thank him for everything. Delete his numbers, block him from your social media accounts. You've to move on with your life. And, if he ever comes back don't welcome him.
I was on the same boat but a different water. My ex told my friends that she never loved me. They forced her to love me. However, my friends knew as I did; she did love me. She didn't want to tell my friends or I the reason she dumped me was that she was seduced by a man who had "good" money. It did hurt, but if I still held on to grudge, it wouldn't help me. She is with another man. I would only be self-destructing myself.
The power to forgive is in your hands. Tell yourself why you've to forgive him, which are the benefits of forgiveness, and forgive him as difficult as it is.