need to vent ( I'm so stupid) advice and guidance needed

So Im lesbian and I had baby with my ex she didn't adopt mthe baby or sign birth certificate. I was so blindly in love that I still gave baby her last name. She was a horrible person and parent so I worked up courage and left I still tried give her chance be apart of our daughter life . However she choose to still be unsporting. I cut my losses and my fiancee who been there since my daughter was one. Her family done the same . We just found out that my ex has been using my daughter on her taxes 😡😡😡. I feel so stupid l,my fiancee was fixing hers so we weren't using her . Then we filled this year and bam 💁🤦. I feel so stupid. We are now doing second parent adpotion process but I just hate this like how could I be so dumb 😭😭😭😢😢😢?? I'm so annoyed and angry.