27 years of compartmentalization of my traumatized inner-child

I’m about to get insurance through my job. My bosses go to therapy and are very supportive. Long story short, I had an abusive older half-brother and my parents were extremely dismissive. Not typical sibling stuff. Like drill-bit in my belly button when I was 4 type stuff. My endearing GF just went on a long trip and it fully activated whatever has been brewing in me for years. Panic attacks. Extreme hopelessness. Abandonment. Racing thoughts. Angry outbursts. Thoughts of self harm. I cannot continue to put her through this. She has her own illness that she’s aware of but it definitely feeds my triggers. I feel like I’m another person when I’m spiraling. I’ve only spoken to her about this so far. My family thinks my childhood “wasn’t that bad”. Idk. I keep trying to self diagnose BPD because I relate to so many of the symptoms. But I know you have to go through rigorous therapy to get that diagnosis. I’m just feeling lost. I’ve always been very emotional. But this is overwhelming for me and my partner. I don’t know what I’m looking for by posting here. Just something to get this off my chest. A few of the posts definitely made me feel better. Some free resources to handle these things would be appreciated. Thanks for reading.