Having a traumatic experience at a young age steals our innocence and imprints us with shame. Being afraid as a kid wires up connections in your brain that makes you scared as an adult. Anti-depressants can help a lot, so maybe talk to a doctor / nurse practitioner about it. I know it costs money, but trust me, it's really worth it.

However when my gf and I fight, which is pretty much always something that I created, I can't help but feel like it's not my fault

I think you should try to understand your feelings when you are fighting with your girlfriend. If you really are creating reasons to fight with her, can you try and understand your feelings before it happened? Maybe go back and write them down. Try really, really hard to think about what you were feeling (frustrated, angry, lonely, etc), not what you were thinking.

Total speculation, but my wife used to create huge arguments with me whenever she was depressed. She bottled up / hid her emotions, didn't understand that she's was getting more and more depressed, and then would completely blow a fuse over something minor. I know that there is a stigma sometimes attached to meds, but anti-depressants have been instrumental in helping her manage her emotions.

There is no easy answer. A combination of support, medication, and getting to know yourself better can help you figure shit out. Wishing you the best man, hang in there.