My gf‘s best friend cheated on my friend

I really just need to get this off my chest and to tell someone, not specifically someone I know personally. A good friend of mine has gotten with a girl from our grade (we are all finishing high school). Through him and his gf I learned about my gf and they were the reason why we have started dating, they helped us to get to know about each other which led to us going on dates and eventually starting to date officially. Me and my gf are very christian, her best friend is too, my friend not so much. Everything is going very well between me and my gf and between my friend and his gf too except for her strict parents forcing her to keep the relationship a secret. We all go out, sometimes double dates. I knew that his gf has had a problem as he wasn‘t really christian and he did get drunk and stuff which bothered her and he knew aboit this too. So almost three months in, I hear about him that they have broken up now. He reveals to me how the whole time she has been talking to another guy, texting him, sending him pictures of hereself (the same she sent to my friend) etc. He had confronted her about it to which she replied „it‘s really not that deep“. Eventually, he confronts her again later because we were on a double date again and she was texting tbat guy even then, so she says that she is sorry and promises to stop which she doesn‘t do.

It was already enough of a bad situation and disgusting, but I knew that the religion part and her parents also played a big role, so I was kind of siding with both of them (obviously calling out that texting the other guy was cheating and not justifiable tho). My gf agreed to that. However, now I also found out from my friend that him and his gf had a short „break“ for a week to think about how they should navigate that relationship and during that week she was going to meet with the other guy, however she didn‘t manage to. I talked with my gf about it, finding out that it was indeed true and that it was some guy who she (her best friend) friendzoned multiple times and kept texting because „he was just a friend“. We talked for a for multiple hours and she did come to realize how all of that sounds and how I believe that her best friend never cared about my friend‘s feeling and just threw everything out, instantly ready to exchange him for another guy while using religion as an excuse. I told her that if she actually wanted a christian boyfriend, she would have at least done the bare minimum of being a christian girlfriend. My gf never justified her cheating and also agrees how terrible it was, but she (understandably) tries to somehow protect her best friend. All four of us agree that this situation will not get between me and my gf and we both reassured each other of that.

However, I am just lost and a bit overwhelmed. I tend to be very empathetic and it really hurts me to even think how it must be for my friend, so I‘m being here for him the whole time. The whole situation also really overwhelmed my gf because now everyone in our grade knows that her friend is a cheater and has to deal with it and my gf is a great friend. I was also very good with her best friend, but now I will never see her in a positive light again, I feel. The more I think about it, the more I realize how fd up it all is and it just disgusts me like crazy.

I am just lost in how I myself feel about all of this and just needed to share it. Thanks to everyone who has taken their time to read all of this.