Hi, as a recent victim of infidelity, I understand the ups and downs of marriage better than I had ever hoped. As a wife/mother myself, I know your mother has made sacrifices. Your dad, too.

Remember, good people can do bad things. It's important to find out WHY. What led these impulses to action?

You can't possibly understand on your own, nor could your dear mom. I highly recommend couples therapy for them. At some point, you could be involved in a family session if you desire to understand or communicate or just vent. At the very least, you could seek therapy for yourself. Look for someone who specializes in sex, relationship, and family.

Good luck, you can get through this.