My friend is having an affair with a married man and I think it's gross. How do I maintain the friendship?

My close friend has been sleeping with a boyfriend from college that is now married with 2 kids, after she got divorced recently. I find it disgusting that she is willing to engage in an on-going affair with a married man knowing he is willing to do that to his wife and children. I look at her differently now. She said she cannot "give him up" but I personally feel he is a sh*tty human being for willingly cheating on his wife like that for over a year. I asked her why not just pursue the relationship and he leave his wife & she said she doesn't even want that - she likes this affair of them having sex in hotels every few months (they live in different cities and both have kids). I said why not find a single guy, and she said it's not her problem that he's married, it's his because he took vows. I agree with her on that point but I don't see how you can be attracted to someone that is willing to treat the mother of their children so disrespectfully. In my opinion this makes him a man lacking in integrity and therefore not attractive. I am the only person that knows what she is doing and I see her differently now. She is also sleeping with another guy down the road from her in between her monthly meet ups with her ex-bf, a parent from her kids school. I now see her as a little whore seeking validation from the wrong places. I don't have a problem with women having sex or even one night stands - but to knowingly have an affair with a married man for over a year I find disgraceful - what kind of man is that and why would you want him if you know he is willing to treat the mother of his kids that way? Am I wrong here or being a disloyal friend?

My friend is having an affair with a married man and I think it's gross. How do I maintain the friendship?
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