Personally I wouldn't fuck her. Had such opportunities, too. Didn't use them. These bitches shouldn't be rewarded with sex for their unfaithfulness. If you're with someone you don't just fuck around elsewhere. It devalues the relationship. And don't give me crap about sexual needs. If you can't fulfill your sexual needs with your partner you have no need to be in a relationship in the first place. If you want to fuck around, stay single and enjoy your time, but don't waste other people's time by defrauding them of the relationship they could have.
