What you are doing is not a betrayal. It is the very thing that could save your marriage and improve your quality of life.
Regarding the name change, my birth father was the one who assaulted me and I changed my surname for the very reasons you stated, that I couldn't stand another day of my signature bearing the name of sheer evil.
A name change isn't NEAR the hassle I imagined it would be. Only once early on did I slip up and introduce myself by my former name, one time when I was preoccupied while I was introducing myself at a business meeting. We laughed it off. I am in California, and it was total a few hundred dollars, a few phone calls and faxes to financial institutions, and it was over. Even the driver's license and passport name change process wasn't a big deal.
Turns out, it's a routine process because of the tradition of women changing their name in marriage. It's just a little unusual when a man or a family unit does it, but still, it's routine for the court clerks. As you can imagine, most workers at financial institutions and offices endure boring and routine jobs, so an unusual name change comes across their desk and they're kind of intrigued. They welcome the break in their routine and want to converse about the name change. I didn't want to talk about it, so I told them it was for business purposes, that my name was being confused with another person of the same name. That always satisfied their curiosity.
You don't need a lawyer. You can do the documents yourself. Or, if you're like me, I was clueless and nervous so I used legalzoom.com. (It probably isn't necessary, though.)
It also helped to go immediately to vistaprint.com and order business cards with my new name. It really helped my psyche seeing my new name in print. It also helped to see the perp's name GONE from my life. You are correct, that it will haunt you both with regret if you pass along the perp's name to future generations.
If you're up to it, do the research on name change and, when the time is right, lay out all the researched information on a table in front of your husband "to ponder."
In my case, my first and last names were the same as the pedophile perp who had attacked me throughout childhood. It's such a relief not to sign his name every time my signature is required. That's a LOT of freedom gained for just a couple of months of transitioning to a new name.
On the other matter, I believe you are right. I am not a therapist or medical professional, but as a survivor I have witnessed that EVERY survivor of sexual abuse that doesn't seek professional help ends up acting out in some unhealthy way, usually in taking up self-hurting coping practices.
You're smart, you're courageous, and you're pro-active. You are EXACTLY who your husband needs for a wife. Even more so, you are making the right moves for yourself and your family's future.