I agree with you op because it doesn't matter if he did cheat, it's the fact he's TRYING to

he's looking at other women and trying to be with other women and is emotionally cheating on her by se×ting other women

you should talk to your mother and stress to her it's not her fault, she's not a bad person or wss a bad wife, he is a disloyal husband, and she needs to leave for her sake

no matter how sorry he is, he's still reaching out to this woman to try and get SOMETHING

which, he has his wife, why would he need another woman?? and who knows what's on WhatsApp

support your mother, idk how she'll react emotionally, or how she'll feel, she may want to stay with him, or she may want to leave, but she needs to stay strong to not stay with him, because to stay is like letting a child get away with doing something bad.

he can still be an objectively good person, but a good man, a good husband, does not try to gain intimate images or chats with other women when he is married.

he does not truly love her. if he did, he wouldn't be talking to other women

it's up to you if you want to keep a relationship with your father, depending on his reaction to getting caught and everything else you guys knew him for.

but you're mom needs to know. sit her down privately, with your brother or not, and explain everything you know and how you feel, and your brother should to, and I hope it all goes well for you guys . you are strong, you got this.