I meant that the wayward spouse may interpret the intervention as spiteful and resent it, and you then have more healing to do that if you had stayed the "nice guy."
Again, I am making a distinction between "shame" and "firm, loving intervention." Christ forgave the adulteress, but He also told her to "go and sin no more." I think as Christian, betrayed spouses, we have to balance forgiveness and compassion, with holding up a holy standard and also taking care of ourselves.
These are difficult questions, and I don't profess to have the only answers to them. For example, we're also called to be good stewards of our family's finances; should we pay for a wayward spouse's cellphone that they use to conduct an affair? Or do we "throw over the moneychangers' tables," so to speak?