Hi Angel,
I know exactly what you're going through. My parents sold my childhood home 5 years ago and it was pretty traumatic for me, even though I hadn't lived there for years. Like you, most of my memories were bad ones, but still, it was the house I grew up in, for better or for worse, and it was hard to see it go.
My mom actually understood how I felt, even though she's not normally the emotional type. Shortly before the closing she took me to the house for the last time. The previous owner had signed their name in the garage and included the dates they lived there. So my mom found me a pen and I did the same thing, right under the first owner's signature. I walked through the house and I was able to say goodbye. I know it probably sounds weird, but I felt so much better afterward.
I hope you get a chance to say goodbye as well.
Take care and hugs,
JG