Pardon any mistakes with punctuation or format, this is my first post on reddit.

I've been with my girlfriend for 5 months. I met her through my college roommate, and her n-count and previous bf count was exactly zero. 2 months into the relationship, we had sex. I had no problems with her at all, I had discovered TRP about a year ago and the relationship was smooth sailing and completely RP: sex 5-10 times a week, very loyal, willing to do whatever she wanted for my pleasure or happiness. HB6 without makeup, can easily boost it to 8 with. However, tonight something caught me off guard.

Tonight, my girlfriend nonchalantly told me that she sucked another guy's dick, he came down her throat, and she swallowed it.

Details: I had already known she had sucked dick before, so that was no surprise. What got me was that she was a swallower. I had never come in her throat; maybe it was some of the inner BP still within me that said coming down her throat wasn't a good idea. When she told me, I suddenly just imagined her doing that. The visual is still playing in my mind, over and over, on repeat. I got myself out of the room we were in ASAP, haven't texted or talked to her in a couple hours.

My question is, has anyone else suddenly come to the realization that their LTR has probably fucked/sucked like a slut with another guy? It was a wake-up call to me, and I felt physically repulsed by her for the first time. Like I said before, the relationship has been very smooth sailing as of now, and the reason this entire subject came up at all was her telling me she would swallow if I came in her mouth and "it's just easier for cleanup." How should I handle this situation?

Thanks for the year of TRP guys, it changed my life completely. I still have ways to go, and I just need opinions and first hand experience here.