24 years old and what the heck is going on in my brain [M]

So too start this conversation, I used to webcam and do dildo play almost everyday for 2 months. Then months later got into a relationship. During the first 4 months of my gf and I’s Relationship I was horny one night and downloaded Grindr. I met with a guy out front of my house in his car. Within 5 minutes we hopped in the back of his car and I bent over , pulled my sweatpants down and he slapped my ass and squeezed it. And suddenly I said “no I can’t do this I’m not gay.” That was the first and last time I ever did that. Now when me and my gf bang I think of a guy fucking me same time. What the heck is going on with my brain lol?