Hey there, and welcome to TeenHelp!
I'm really sorry that you've been going through such a rough time. I want you to know that there's nothing wrong with you for turning to self-harm, it is simply a way that some people try to cope with their overwhelming emotions/thoughts. However, it isn't the best or the healthiest way and can even become addicting so it's better to find alternatives. I know it's hard to stop, it's still hard to stop even if you've only done it once but the more you do it the harder it will get so I really do recommend trying the alternatives in the forum Etari posted for you. Try as many as you need and don't be discouraged if one doesn't work because there's always another.
Also, as soon as you can identify the reason why you want to self-harm(to calm down, to feel something, to see blood, to feel more in control, to express yourself) you can gear your alternatives to things that solve that purpose. (For things like seeing blood you can use a red marker and draw on your body or draw a picture of yourself and mark it up red) I've found that the need isn't really in the self-harm, it's in what it does for you. So if you can find an alternative that does the same thing, even if it's on a less intense level, it can be really effective in helping you deal with urges.
Also, on a side note I haven't run into any idiots on this site really, a lot of the people on here are really here to help whoever they can and give really great advice. I think you'll be able to find support here and you can
PM or
VM me anytime if you need to talk.