Help! My gf kinda pooped on me?

My (28m) gf (28f) did something so gross during sex that I still don’t know how to feel about it. We’re together for 1 month more or less and till now everything was going alright, still tryna figure out our thing in bed. Im not a super kinky kind of guy and I didn’t think she had any weird kinks or anything, till now everything was vanilla stuff and she never mentioned anything. On to the story, we’re basically doing it doggy style and she seems like she’s enjoying herself and at some point I realise she’s enjoying it very much. Like VERY much. Again no complaints here, I want my partner to feel good and I’m doing everything in my power to do so. She’s clenching the sheets, screaming, backing up at me. Not gonna lie, it was a bit scary, I’d never seen anything like this before irl and I kinda got caught up in the moment? I mean I still cant believe I didn’t realise it sooner. Anyway I kinda pull back a little and look down. Boy I shouldn’t have done that. She’s clenching a big ol’ poopoo in her bootyhole, a huge monstrosity almost as big as my thing and I realise the tip of that thing was touching my pubic area. I almost gag (still trying to be chivalrous and shit) and ask her if she’s alright. She says its perfect and to continue but I ask her again if she wants to take a break or smth. She’s like no no dont stop and so I do the unthinkable and get on with it. I’m trying to position myself as not to touch it but every time I’m going in, the thing is going out. I don’t know what to do, I’m disgusted and that thing is going in and out, in and out like an organic dildo. I couldn’t do it anymore, I just stopped and run to the bathroom and Im thankful I threw up in the toilet and not on her back at this point. We showered (separately) and obviously we had to talk about it. She was mad and couldn’t understand why I stopped and I couldn’t get myself to explain what happened back there. I mean its super embarrassing, how could she not know??? I told her. Guys I really did. I told her and asked her wth was that and why didn’t she stop and go to the bathroom. I asked her, I gave her a chance to go, I’m not a fucking monster. She said it felt GOOD like a threesome or smth and it felt way too GOOD to stop. WHAT THE ACTUAL FUCK? And that I’m weird and pitiful and I don’t understand these things because I’ve never had anal done on me? This is so fucked up. I don’t understand it and I don’t think I want to. I cant even look at her, I just went home and said I’ll think about it. What was I supposed to do? What am I supposed to do now? She said its something women do and it feels incredibly good, like a threesome but without all the cheating. I don’t think I can live with this guys. It’s waaaayyy out of my comfort zone. Its on my gagging zone. What do I do?