I've been a little fool.. Need Grace

I love my husband to death. Wasn't sure I was in love with him. We've been emotionally separated. I started flirting with ex husband. He has been in a rocky relationship. It's been 7 years since I lift, with my now 9 year old. He treated me like a dog. Drunk and abusive. We talked about that this week too. I was thinking about moving back with him. Last night when I went to the gym. I watched my husband play with our 2 year old. My heart ached. I can't do this. Today we went house shopping and I can't leave. I praying my ex will understand and back off. Everyone told me to pray and seek God. I wanted to do what I wanted even in these 4 days. I need God's grace and forgiveness. I want my marriage to work. I'm so so sorry. I feel like crap already.