Did I do the right thing by breaking up with my girlfriend even though she asked me to stay? (17M, 18F, 2 years of relationship)

I had a 2-year relationship with a girl (18F) who seemed fine from the beginning, but over time she showed several serious emotional problems. She was very insecure about her body and resorted to self-harm when she was in trouble. At first I (17M) did not know the extent of his internal injuries.

I supported her as much as I could: I put aside my things, I gave her time, affection, outings, gifts, and I even wrote poems to make her feel valuable. However, she often treated me badly, making fun of me with her friends and making me feel guilty about her meltdowns.

He was only sweet when he wanted something intimate, like sex or photos. Still, I stayed with her because I really loved her. At one point I asked him for some time to get help so we could have a healthy relationship. He had supposedly gotten better, but I later discovered that he was still self-harming and was hiding it from me.

One day I hugged her and felt wounds on her arm. It broke me inside. At that moment, without thinking much, I ended the relationship. I was mentally and emotionally exhausted. She begged me not to do it, but I couldn’t take it anymore.

Now she talks bad about me, blames me for everything, and has shown intimate photos that I sent to her friends. It hurts a lot, I still miss her, but I’m confused and I need help to understand if I made the right decision.

TL;DR:
I was in a 2 year relationship with a girl (18F) with serious emotional problems. I (17M) did everything I could to support her, but I felt more and more damaged. I ended it when I discovered he was still self-harming. I feel bad, but I couldn’t take it anymore. Did I do well?