daughter helping mom out

Help please. My dad has been having affairs on and off throughout my parents' marriage. He even has one ex-girlfriend claiming they have a son. Recently, my mom left him because she couldn't swallow the shame and disrespect he keeps causing my mom and our family by having affairs with people who actually have common circles as ours. His current girlfriend is brave enough to stand up for their relationship (she tells her friends, they've been seen together, she goes to my dad's events) and even messages my mom when my mom doesn't even do anything to her. This is really hurtful to our family. We need assistance on how to go about filing charges (Rep Act 9262) on the grounds of psychological and emotional abuse due to repetitive extramarital affairs, as well as minimal to no financial support. We also hope we can file a case against the girl (Art 26 of the Civil Code) for disturbing our peace and for meddling in family affairs. May we know the requirements as well as needed proof for a strong case? Thank you.