Although you may have a hard time believing it right now, God still loves you, and He is even more concerned about what's happened to you than you are. The Bible says, "The Lord is gracious and compassionate, slow to anger and rich in love" (Psalm 145:8).
You see, what your husband did was wrong, not only in your eyes but in God's eyes as well. When you were married, he took a solemn vow before God to be faithful to you until you were parted by death. But he chose to break that vow by becoming involved with another woman and eventually turning his back on his marriage vows. In other words, don't blame God for what happened; your husband alone is responsible for what he did. The Bible says, "When you make a vow to God ... fulfill your vow" (Ecclesiastes 5:4).
But I also urge you not to let anger or bitterness hold you captive any longer. If you do, they will become like an acid eating away at your soul. I know it's hard for you not to focus on the past, but if you do, you'll become a prisoner to its hurts and emotions. Instead, ask God to help you refocus on the future.
How can you do this? Begin by confessing your sins to God, including the feelings of anger you've had toward Him. Then ask Jesus Christ to come into your life and sweep it clean, and then by faith trust your future into His hands.