How do I look at my dad the same 😭😭😭

I'm 18 and this happened when I was 8 or 9. I got into my parents "naughty box". At the time I didn't really understand what I was looking through but it just hit me now! It was the typical sex stuff like a vibrator and restraints and whatever but there was a gag. And why the gag has me freaked out is because I vividly remember the gag saying Good Boy on it. I was confused as a kid and thought it was some type of ball but realizing at 18 if the gag said good boy this means my mom used it on my dad! And why would she need to use a gag on my dad??! It made other things I found in there seem even worse because she was probably using those on my dad.

I know this post is stupid but after this realization I'm having a hard time looking my dad in the eyes. Him and my mom have a very wholesome marriage. My dad has also always seemed to be a strong guy on the more masculine side so I can't believe he participated in something this degrading. I know everyone is going to tell me it's not my business and to stop being a whiny brat but for a second imagine it was your parents. How would you feel

Edit: I understand my parents have sex. I know where I came from. Where in weirded out is my dad is an extremely masculine person. I can't imagine him being "submissive" to my mom and it's weird