What your ex-husband did wasn't just hurtful it was also wrong, not only in your eyes but in God's eyes, as well. It was wrong for him to break his marriage vows and be unfaithful to you, and it was wrong for him to abandon you and your children.
Yes, you are understandably angry at him but has it ever occurred to you that God is angry at him also? To put it another way, God hates what your ex-husband did even more than you do, for God is pure and holy, and sin is a offense to Him. Your anger may not be pure but God's anger is, for He loves us and hates what sin does to us.
Some of the most sobering words in the Bible are those that warn of God's judgment on sin. It says, "Be sure of this: The wicked will not go unpunished" (Proverbs 11:21). This is why you can yield your anger to God, and leave your ex-husband's future in His hands. The Bible says, "Do not take revenge, my friends, but leave room for God's wrath, for it is written, 'It is mine to avenge; I will repay,' says the Lord" (Romans 12:19).
Pray for your former husband that he will repent and come to Christ. And pray daily for God's strength and wisdom as you raise your children. Don't let anger poison you (or them), but ask Christ to fill you with His love.