I was 12 when my aunt,

I was 12 when my aunt, my father's cousin brother's wife, and her daughter visited our home. When they went back they called my father and i dont know for what reason said my father that my mom took money from their purse. My father and mom had a big fight but eventually everything got settled, my mom was innocent. After some months I saw my father's chats with my aunt. There were some flirty texts from both ends which were not appropriate. I decided not to tell anything to anyone as I was very young and immature to deal with it, but eventually my mom found out and she confronted my father and my father said sorry to her and promised her not to repeat any such thing. Now I'm 19 and I again found out that father is still in contact with the woman, regularly calls her and some suspicious texts are still exchanged between them. To understand my situation you have to know that my father is like the perfect father. I've idolized him all my life like any other son would do. He takes care of his family especially my mom very nicely. He fulfills all our desires and is really good Husband. He even does a lot for my grandmother, my mother's mother. The question in my mind arises that if he is actually cheating on my mom for such a long time then why would he do sooo much for her amd her family, you could never say or doubt about his these activities but here it is, the messages and the regular calls. I don't understand what should I do. Ever since I came to know about it I'm not able to see him with normal eyes, I've started to hate him and think every act of him as fake and started questioning my life. Should I confront him and how?