Yeah, it hasn't been that long. Five years since your Dad died, but you still experienced ongoing assault from the mom's boyfriend.
Don't be expecting perfection from yourself. When we learn new behaviors to old traumas we rewire our brain. It can take some time. Right now your brain is wired from the old traumas, and when you experience it all over again while telling yourself it's over. That's what happens to me. With time it gets better.
Guilt might not be what you are experiencing, it's just that you don't have a better word for it. It's the chaos, confusion and fear that you relive. What's the word for that? Cha•fus•fear? And a host of other feelings. Guilt just pops up to cover it all.
I've shared that even after decades of safety my heart pounds when I unexpectedly hear screams or swearing in anger far off. If it startles me my body goes into reaction mode while my head tells me, nothing is wrong, nothing is going to happen. But I have to wait it out, and settle down. It's not disrupting my life and I've learned to handle it. My husband understands and works with me. You will figure this out. I think the key is to expect that it will not disappear immediately and not be upset about it, but work with it. Learn what to tell yourself to talk back to the voice in your head that says "guilty". You have to teach yourself. Like I said, read, write, pray and post. It will get better.