Why do I feel like I need to hurt myself in order to feel better?

Because you don't want to feel only emotional pain. Emotional pain doesn't leave visible scars, and maybe you want to remember

Because yer hurt on the inside and yer want to feel that pain physically so youse hurt yourself in order to feel that pain and to feel good about yourself but the reality is yer just causing more pain which don't help

Basically the mentality of " It worked once; so it will work again." It's a coping mechanism; my brain believes that hurting myself will make me feel better because that's all it knows. In any situation where I am unclear of my emotions, or they're too much, my brain automatically goes to an unhealthy coping mechanism because it's how I have always made myself "feel better" when in reality, it only helps for the moment. It only relieves some of those feelings I couldn't express, but it does nothing for the long term situation I am facing. But in the moment, I'm not thinking of the future. Just now. It's an impulse.

Human bodies are amazing; when we get injured our brain takes charge, and pumps out lots of chemicals that create healing. Some of these create a temporary state of euphoria, others create a numbness that many might welcome. So when I self-injured, I was "getting high." But like any other drug, it takes more and more to get the same feeling, until it goes too far. You may feel "better" but it's not a lasting better, only temporary. Some people self-harm simply to feel alive. I guess we have to keep in the front of our mind, like a giant neon sign, "This will NOT help you" in the long run. Just as an alcoholic might think just one drink will help them face their problems. Self-harm is often an addiction.