Took her to the family reunion

Split in April when he said he wasn’t in love anymore. Truth was he had a gf. Two months later he introduce our daughter to the gf. Now 3 months post split and he’s met her kids and took her to his family reunion this weekend after they took the kids boating the previous day. A memory popped up from a year ago on my phone of us boating as a family. She is his friend’s wife. They still live together. I’ve filed for divorce. He has no shame and just replaced me. My daughter has been sneaking off on her bike to meet to gf on her lunch break. She’s been extra disrespectful to me lately and I know it’s his manipulation and influence. My head is ready to explode.