steadfast1973 asked about your friends,
Did they encourage behaviors that led to the A?
Very good question. Note that the "encouragement" doesn't have to be at all explicit or overt. It can simply be that their lifestyles (e.g., if they're single and dating around) or your conversations with them (critizing spouses or significant others) made it easier for you to have an affair.
Another way to put it is whether your friends are "friends of the marriage"? Does being around them help your marriage? If the answer is no, even if being around them doesn't actually harm your marriage, I'd say defer to your BS's wishes, even if it makes you feel disloyal to your friends. If the answer is yes, that being around them actually helps your marriage and makes it easier for you to stay faithful, then talk to your BS about it.