What should I do about my cheating father?

So I've caught my father cheating on my mother a while ago.. I told my aunt and she immediately made my father end things
I was extremely angry at him although he is a good father but he neglects my mother a lot and I recently found out he has been spending time with the other woman although my mother is very good and affectionate with him
I still can't move on after months.. I'm still always suspicious of what he's doing.. it's also making me sad because I bumped into his mistress a while ago and I have a feeling that he didn't end things like he said he did
It's affecting my relationship with my boyfriend too..
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Thank you to those who were understanding I appreciate your help a lot
I understand I need to tell my mom but I don't want to hurt her.. maybe I'm wrong but I know she will be deeply affected by this.. this is why I told my aunt first
I can't stay out of it.. I've seen my mom committing her whole life for my father and she was always loving and caring with him.. she doesn't deserve being treated like this
I still love my father but I'm still hurt by him
I've always viewed him as someone perfect
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I'm not going to reply anymore but I'm sure now that everyone justifying it is also nothing but a CHEATER or is in the same situation now

If you do not want your kids to get involved then don't fucking cheat on your partner and if you think it doesn't affect them then you are WRONG
What should I do about my cheating father?
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