How to get a guy to leave you alone?

[teeny-tinycrowd980]

I am 16 and this lad is 17. I started talking to him about a month ago. He has problems at his home and so him and his dad are always fighting, so when he got kicked out and asked to come round for a few hours while it cooled down at his I said yes. However, since then he has slept round at mine (uninvited!!) several times, in half term he stayed for 5 days before reading my messages :/ where I basically said he was being awkward by not getting the hints and leaving. So after he stormed out I didn't speak to him for 2 days before having his friend knock on my door with him, only to find out that he had cut his wrists, drank bleach, got smashed and tried to overdose. Of which he blamed on me. He has told me that he loves me and I have told him I will not go out with him. However, I think he is now stalking/harassing me, as he has been turning up (apparently as a complete accident) wherever I am at the time, even when I have not told him where I will be, including late at night. Today he decided again that he was coming to my house (he never gives me a say in it, just tells me he is coming round). He has been here for over 5 hours now, and i'm afraid he will sleep the night again and then not leave! How do I get him to stop liking me as he doesn't seem to be getting any hints and I am running out of excuses to force him not to come round! I need a way that will not upset him though as I do not want him to self harm again.
Any help is VERY appreciated, me and my mum are out of options!!