Caught girlfriend having sex with another guy, after he left she started blaming me saying I made her do it, our friends say to forgive her, what do I do?

Our friends said to just forget about it and that she was just lonely, her female friends told me to stop being such a whiner about it and that quote on quote, "all girls just like to have a little bit of fun and excitement sometimes with other guys", I really like and honestly I do feel a little guilty even though I don't know why because I haven't done anything and I've treated this girl like girls talk about how they want to be treated, we have fun together, we spend time together, go on trips, I even get her the gifts she wants, she loves roses and I always buy her flowers, it's not cheap but yet somehow it's my fault, I asked this question on another forum and was attacked by females saying that I was wrong and that having fun and buying flowers isn't enough, well that's not all i do, I'm not going into depth, somehow it turned into a giant fest of ganging up on me, I honestly felt like a criminal/garbage after reading all the comments on that post, am I really in the wrong to be upset?
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To add we have been together for 6 years and I planned on proposing to her
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The wife just text me saying she is indeed pregnant, we were talking and it looks like we aren't going to tell after all, we are just going to keep this our secret. Thank you all for your help ✌️️.
Caught girlfriend having sex with another guy, after he left she started blaming me saying I made her do it, our friends say to forgive her, what do I do?
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