Friendship or more?

Hey guys, Any advice you can give on the below would be greatly appreciated. Abit of Background: I'm in a long distance relationship and have been for about 2 and a half years. My girlfriend goes to university at the other end of england to me. We see each other for a weekend every 3 weeks. The Story: Last year I did a year long work placement in a different city to the one I go to university in and so had to move away (I'd been with my girlfriend for a year at this point). During that year I could only see my girlfriend at best once every 4 weeks. For half the year it was once every 5 weeks. Needless to say this put alot of strain on our relationship to the point where it felt like we just friends and not a couple. We decided to go on a break to have a think about things. During this break I met a girl in a night club. I'm two years her senior. We spoke abit (as much as you can in a night club) and danced abit (in an unusual fashion) and generally clowned around. We exchanged phone numbers and went our seperate ways. We met up the following week. She was a shy girl at first and softly spoken. We met a few more times and she came out of her shell. We became good friends over the following months. She is a very sensitive, intelligent and the most intriguing girl I have ever met. The more we saw each other, the more we started to like each other and started to see each other (after a fashion). As I got to know her it became clear she had some problems. I could see scars on her arms where she looked like she had been self harming previously. She told me on a few seperate occasions that she wanted to kill herself. This worried me greatly as not knowing her for very long I didn't know if it was a cry for attention or she was being serious. To this day I still don't know which it was, but shes still among us (thankfully). I know this reflects badly on me, but the emotional instability really bothered me. Also when I saw her she would always be texting other guys and talking to them online etc. We weren't going out or anything official so she had every right to, but I didn't make me want to trust her. She never really opened up to me. If she had a problem she would start to talk about it, then stop mid conversation and say she didnt want to talk about it anymore. Things carried on like that for about 2 months. I had been talking to my girlfriend through out this and we both decided we wanted to give things another go and work through the problems we were having. I told the girl I had met about this. We still saw each other abit, but in a friends capacity and not as frequently The last time I saw the girl before I moved back home she turned up drunk and broke down in tears saying she didnt want me to go. After the year was up I moved back to my home town to go back to university for my final year. That was about 7 months ago now. Since then I have been to see the girl I met on 3 different occasions, both of which have felt abit awkward. She is on her 2nd boyfriend now in that 7 months. She smokes weed regularly, is not turning up for most of her university stuff, has changed friendhsip circles a number of times, has been prescribed anti-depressants and is having serious financial troubles (this has all happened in the time I have known her - about a year now). We haven't really spoken properly for the past month and half and on the rare occasion we have spoken it has been me who has initiated it. It's as though she can't be bothered anymore. The Problem: I keep thinking about the girl I met even though I am with my girlfriend. I keep wondering if shes ok. The girl I met is nothing like the type of girl I would normally go for. I don't do drugs, I work very hard at university etc But I keep thinking about the girl and wanting to look after her. I want to make all the bad things in her life go away. I guess I care about her alot.