I'm honestly on the verge of a breakdown at the moment.
To summarise: I have two main issues with undertones right now.
The first is that I'm...falling in love. I can't stop thinking about this person, I genuinely care about them. I've had so many urges to call them "love" or "sweetheart", etc, and only barely managed to catch myself before saying so. I find them, visually, adorable, and their personality is...I just want to protect them, they're marvellous in my eyes. I've even fallen in love with most of their characters, spare the negative ones. Issue? They're a world away, an internet friend. And...I've got a girlfriend. She's a dream, I love her, and I don't know what to do with this anymore. I did tell this person both that I have a girlfriend and that I'm falling in love with them, but I don't think they heard the second bit. I'm honestly glad.
My second issue is that...there was this other girl that had a crush on me. A massive crush, really, I honestly believe she was bordering on having an obsession with me. But, it got scary after a while.
She'd blackmail me, using the scars along my arms as material, and she'd become so...so clingy. We had a story going on, a kind of roleplay, and, you know how your behaviour/personality can be reflected through your own characters? Well...
Her main character was loudly crushing on my main character, and he was being...sexual. We're both under eighteen, so this alarmed me. Her character, whom we shall call S, was being very intrusive with mine (K), to the extent where he'd even crawl into K's bed while K slept. S would even rub against him at points. I made it clear through both myself and K that K really didn't like this, but this behaviour only shifted to another character. I drew the line when the new one, H, came in.
H stalked K. Stalked him through states entirely, even after K made it VERY clear that he wasn't interested. This was just a fraction of what it was like in real life, too.
In real life, she confessed her love to me on my birthday. I can never forget it now.
Whenever I had her over, she wouldn't leave me be, and acted like a wounded puppy whenever I pulled my arm away from her frankly tight embrace. She was harsh in showing how she cared (calling me a stupid Italian, in reference to how I was apparently like Ezio Auditore de la Firenze from Assassin's Creed), and, as mentioned before, started to blackmail me.
After mulling things over, and with several other unnerving behaviours from her, I stopped talking to this girl entirely.
She never stopped sending me messages over Skype. I ignored them all.
When I talked to her again, she was very forceful, demanding I tell her where I'd been and what was happening in my life despite me making it obvious I didn't want to talk about that.
I stopped again.
I never told her why I stopped speaking to her, because I didn't want her to take her own life. I didn't want that guilt on my heart, and I knew that she'd kill herself if I told her outright that I didn't like her, and that she made me uncomfortable.
Now...today, this backfired. I received her suicide message an hour or so ago, and I'm in a state of numb shock, and sadness. I regret everything. I know it's my fault.
I don't know how to make my way through this. Help?

Christ almighty, she's alive..

Talk to her. Like now.

Alright, so, um...
Kind of a big update on the whole situation, because I still need help here.
When I told the girl I have a crush on about the suicide attempt, I was hitting a very low point. I couldn't concentrate on our usual, marvellous conversation in the end, so she decided to call me via Skype. The call was shoddy, really, due to her relying on 3G on a bus home, and I couldn't hear her that well. I, thinking that she couldn't hear me either, confessed my feelings and promptly hung up.
Fast forward to today, and we're having a deep talk, when we /both/ confess again. She heard me, it turns out, and she feels the same.

I haven't heard back from the other girl, but I'm hoping she's alright. Her mother has told us that she's doing fine.