Oh Christ OP, here's my story, because I hope I don't go as far down the road as you and this is a LONG story.
I met this girl online when I was 13. Shared similar interests, hobbies etc. I was friends with her for about 4 years, When I was 15, I'd been 'dating' this girl from California, and all we really did was do online sex roleplays all day. I thought I was in love with her, but it turns out she'd been with 3 girls behind my back. I was crushed, devestated, almost to the point of suicide.
But the Texas girl helped me through it, and over a month, I felt kinda good again.
When I was 17, she confessed that she liked me, and I liked her too, I'd just thought she had a boyfriend. So we started 'dating', first year and a bit was bliss, it was awesome, nothing was going wrong. Then she said that she'd fallen for my friend, and he'd told me straight away anyways. This went on for a couple of months, I didn't stand against it because I loved her and was afraid I'd lose her. They'd ask me for permission to have 'sex' and I just allowed them. While it might not seem like much to you guys, I hold sex as a deep, romantic thing, and I cannot find random girls attractive, I have to get to know them, and since I was (and still am) a Mega Virgin 2.0, it hurt. But eventually they broke it off because my best friend saw it was hurting me really badly, and it resumed to be good again for a few more months.
She'd fallen for this guy at school, he was mean to her at times, would randomly just lash out and such. She told me everything they did together, and it was really this really big struggle between me and him for ages. She left me a few times for him and such, but after 8 months, they broke up and it was me and her again. Things kept going on and off between me and her for a while since she couldn't get over the other guy and I was getting paranoid and depressed.
I have another best friend who was gay, who I'd known for about 5 years. We were really close, so close that during my bisexual phase I told him I'd go out with him in the case we both became single. We hung out all the time and did everything together, it was awesome. Then one day my (now) ex told me that she loved my best friend and he loved her back. I confronted him about it and he said that it wasn't true and such, and although wary, I believed him and continued. Eventually he confessed that he did love and and had done so for a while.
I started cutting him out of my life, until I recieved a phone call from him, where he was crying and screaming for me to forgive him, promised that he wouldn't go for her anymore and everything. I eventually gave in and let him back in. Later this year I'll be going to Georgia for my other best friend's wedding (who was the one who first fell in love with her while I was with her) so I secretly got back together with her when she sent me this long email saying how wrong she was and such. This went on well, but one thing led to another, I looked on Facebook, and she and him had made their relationship official.
I was crushed, my dream of four years to go over and see her was gone, I lied to so many people that I wasn't with her anymore, and my best friend and the girl I loved with everything I had stabbed me in the back and I hadn't even met her.
This is about 3 months ago.
I don't drink, because I don't have anything to drink, some days I'll fall into a heap, other days, I'll hate being in my house. I've been slowly doing worse at work, and my doctor has been increasing the dosage on my anti depressants. I've had some more friend's stab me in the back for the guy who took my ex, and my other friends (and family) are getting pissed off because I freak out whenever I go into town and I'm just generally in a shitty mood. I've been trying to move on, I have a massive crush on this girl, who I'm not sure if she likes me, but she says that she doesn't want to try and go out with anyone until high school finishes, and that she has been abused in the past by male figures.
Where does this fit in with you?
I've had to cut out a lot of people, change email addresses, and just ignore some things and I think I'm slowly getting over her. But in this process my personality has changed drastically; I get aggressive, I don't trust anyone anymore, and I just take things that most people say as bullshit. What I think you need to do, is tear out everything involving the girl (start hating her if you have to) and just start yourself over again if she affects you that much.