Don't apologize for struggling. Don't apologize for feeling bad. And don't apologize for turning to what you thought would help. Because none of those apologies are necessary at all.
Your struggles aren't something you should apologize for. We all struggle in life, some more than others, some less. No one should have to apologize for struggling with anything, and that includes you.
Your feelings are valid. All feelings are valid. All feelings have some sort of reasoning behind them, and all feelings should be seriously considered. Don't apologize for not feeling a certain way, because that's unnecessary. Any feelings you have are fully valid and real, as all feelings inherently are.
Don't apologize for trying to help yourself in whatever ways you can. The idea behind self harm helping makes enough sense that, in the moment when your emotions are high and your logic isn't necessarily, it can seem like the best option available. It can be hard to see other ways, as well.
Someone once told me that instead of saying sorry, you should say thank you. It helps you feel better, and it helps the other person feel better. You don't have to follow this idea 100% of the time, or even 50% of the time (I know I don't), but it's something I thought might be helpful. I don't want to see you feeling badly about this, because there's no need.
We are here to help in whatever ways we can. We all offer our help willingly, because we all care about you.