<human>: I have been hanging out with a group of 3 married couples regularly for the past 3-4 years. The ages of the couples currently range from 25-35. There has been nothing out of a friendship - I just have a genuinely good time hanging out and having a couple beers with them. Since I've been dating my boyfriend, he's also enjoyed hanging out with this group of people. Since I must leave for school during the week, he spends a couple nights a week with them. I do not have a problem with that.

My boyfriend told me the other day at the bar that he had news but was hesitant to tell me - he didn't want my opinion to change. Husband 1 told my boyfriend that he let wife 2 perform oral sex on him several times, but his wife didn't know. Husband 1 said he felt bad about it but didn't plan on telling wife 1. Husband 2 would watch while wife 2 would perform oral on husband 1. 

This news has sickened me as I misjudged their characters. At least 3 people were involved in an affair and deceived wife 1. My boyfriend would like to continue to hang out with the entire group as frequently as he did in the past. Would it be stepping out of boundaries to ask him to at least cut back the frequency of their interactions? If so, how should I go about it? I feel uncomfortable asking my boyfriend to limit/end friendships; however, this goes far below my morals.

Can you condense the text into a few key points?
<bot>: my boyfriend hangs out with couples that openly engage in an affair- how do I ask him to terminate or limit the friendship?