First off, don't listen to your husband's justifications for lying to you. Like gmc said, that is a false equivalency. You would be telling your parents about something that happened TO you. He was actively deceiving you and hiding choices that HE made from you.
Re: telling, I told everyone on DDay. My parents, my brothers, my grandma, his parents, his brother. I didn't even think twice about it, it was my first instinct and I just went with it. It was a whirlwind, but it was like my brain just knew what it had to do.
My XH would tell you that this is one of the reasons he had to take it to the level that he did and actually leave me for her. Because I'm just too stubborn, have to have everything my way, couldn't keep stuff to myself, had to get our families involved etc. But he didn't view it how I do - our families were already involved. He had used them as unwitting pawns in his lies/schemes. They deserved to know the truth just as much as I did.
I honestly think that is part of why my brain went into overdrive and I notified everyone. It was like I instinctually knew that this is what needed to happen in order for me to feel safe. I needed it all out in the open. No more hiding from anything.
I agree, it will make people look at the WS differently. But, IMHO, if the WS cannot humble themselves to admit to and fully own the A, including making amends to the BS, but also any other family members or friends, then they aren't willing to truly be held accountable for their selfish choices.
It wasn't the outcome I wanted. I definitely didn't ask for him to leave me for her. But, I choose to view it as having freed myself from a partnership with a person who refused to be held accountable for his actions. If he couldn't handle my friends and family being angry at him for choices that he made, well, then he didn't deserve to be with me, or to even spend time with my awesome family.
If you tell, and he can't handle it? Maybe he's not such a good candidate for R.
FWIW, my Dad was in poor health on DDay, so I understand your concern. In fact XH was carrying out his affair on days when I was visiting my dad in the hospital. By the time DDay rolled around, we were still very much in the dark about what was making him so sick. Lots and lots of doctor's appts and hospital visits.
I still told him. There was just no way that I could keep that from him. My hand was forced a bit, I mean I had nowhere to go and ended up moving into my parents' house, but still, I could have given another reason why we were separating. I wouldn't have been able to keep that info to myself, though, I was so distraught.
My parents reacted the way I would have expected them to. Went into instant "fix-it" mode, came up to LA, helped me rent a U-haul and get all of my stuff out, then got a hotel room and stayed with me for a few days while I cried. Then we rented an Airbnb and they took turns coming to stay with me since I couldn't function on my own.
It sounds like you have a close relationship with your parents. I think they will of course be very sad to hear what you are going through, but I assume they would also be happy to support you through such a difficult time in your life. I love to see my DDs succeed and be happy of course, but I also take great pride in knowing that they can come to me with their problems and that they feel comfortable enough to let me be their shoulder to cry on.