Teen Relationship Problem? Help Me Please? Suicide Involved.?

Okay so i have two friends. Alexa and John. They are both teenagers. John is a lot more in love with the Alexa than she is with him. They have been together twice already. The first time they broke up was because of the John’s ex, Danielle. His ex is constantly in his mind, and when he moves onto another girl, Danielle gets jealous and tries to seduce him by kisses, flaunting, sexual talk etc. He, obviously finding her attractive, falls for it. Danielle does not like the girls he moves onto, she didn’t like Alexa and she would even tell him so. However, when he falls for the Danielle’s tricks, she’s only doing this out of jealousy and when she is successful in breaking up his current relationship, she moves on herself and leaves him stranded. This was why they broke up the first time. However, when he realized what Danielle was doing to him, he ran back to Alexa, he missed her, he claimed to love her and said he was stupid. So Alexa gave John another chance and they got back together. They were fine for a while, until Danielle found out about this. Now Danielle and John had a fight over her playing with his head like that and didn’t talk for a while. John and Danielle go to school together, they see each other everyday. Alexa goes to a school far away from his, so they barely see each other and are limited to text and msn communication. John still has feelings for Danielle deep down, but Danielle is just mischievous and jealous and likes to mess with him. So the second time around when they were together, things were going well. But when Danielle would see John at school everyday, she would be tempted to hurt him again just to satisfy herself. So she did. She repeated herself again and he fell for it. Alexa and John were having their own problems and he saw Danielle as comfort and that she would “always be there”, especially when Alexa wasn’t. Whenever Alexa and John talked, he ALWAYS brought up Danielle. It started to annoy her and her friends. They had a fight one day, and with John thinking “oh i still have Danielle”, he ended the relationship, again. The next day, Alexa saw pictures of him and Danielle on facebook of him kissing her and holding her. She checked the date of the pictures and they were taken while her and John were still together! She confronted him and forgave him thinking that “he simply can’t help it and at least I’m out of the relationship”. He felt like an idiot. He thought that he hurt the only girl he ‘really loved’, and started hating himself. He wouldn’t talk to anyone, laugh and claimed he was going to kill himself over and over. He felt like a dumb failure and disappointed in himself. He begged for Alexa back, but she was tired of his obsession over his ex. Then again, she still likes John a whole lot, and can’t help to feel butterflies around him. Plus she was worried about him, because he decided he wanted to kill himself in a river at a fixed time and date and everything. He wrote her poems and cried several nights, but she was not that deep in love, but she still cared. He is not as suicidal as before but is still considering it if Alexa disappoints him with her ‘decision’ to take him back or not. She still likes him but has honestly lost hope for him and trust. Up to this day he is still awaiting her decision, he is still sad but hopes that she’ll forgive him. He promised her that he would get over his ex, Danielle, but he also has twice before, and failed. Alexa doesn’t know what to say, she wants John but the John she met, not this complicated one. He is overly dramatic but claims to love her and that he will try. But they’re no guarantees because we can’t tell the future right? Should she take him back or move on? This will risk his health and increase his depression. But if they get back together, this may hurt her or put her in the same state. WHAT SHOULD THEY DO? SUGGESTIONS OR ADVICE PLEASE!