TIFU by discovering the emails my father sent to his lover while he was in a marriage with my pregnant mother.

Earlier today, I logged into an old email account that used to be my father's email many years ago. I had done this because I was trying to recover my old account in Roblox and the email that was tied to the Roblox account was my father's old one. After logging into the account, I look through, trying to find a password recovery email for my Roblox account. Instead, I find several emails containing weird titles to a person I had never heard of in my life. Turns out, these emails I had found were from my father and were sent to his lover who he had cheated on my mother with.

I felt sick to my stomach.

My mother had previously told me that my father had cheated on her while they were still married. Despite this, seeing the actual emails he had sent to his former lover made me feel so disgusted. As I am typing this, I just cannot stop thinking about those emails as they really creeped me out and have made me dislike my father even more. I know I can't tell my mother that I have seen these emails as it would be rude of me to bring up old history and I do not want to upset her. I just needed some place to vent and type this out.

TL;DR: I found old emails sent by my father to his lover and I feel disgusted at his actions and it will change the way I look at him for the rest of my life.