Should I contact this girl again?

When I was in my late teens I found this girl online through a social networking site and got to know each other quite well online. She used to tell me some pretty personal and awful things in her life. I guess I was a good listener. The following year she contacted me again and came down interstate to stay for a visit with me.

Unfortunately things didn't go so smoothly. I felt uncomfortable spending so much time with someone I just met for the first time in real life. Also I wasn't particularly used to spending a lot of time with a girl at that point in time. She on the other hand has had quite a few boyfriends and stuff and I felt slightly intimidated in the bedroom. Also she smokes and drinks and our lifestyles are quite different. ( I don't smoke, social drinker, eats healthy, goes to the gym)

I didn't treat her as well as she probably expected, we were getting into arguments and it was quite bad at times and now when I look back I feel so much guilt and feel haunted by some of the memories even though its been a few years. We did however have good times too where we had a good laugh, enjoyed being around each other. But the bad things probably outweigh the good, I won't describe them here as they are embarrassing.

Anyway after she left I was in a bad way. I was depressed and had to be in hospital for a while as well. I've come a long way since and doing much better. About a year after I sent her a message. Anyway couple months later she contacted me again to come over saying this time might be better. I said no as I was going on holiday for a month. I kinda felt like she was trying to use me and perhaps my reply didn't sound so friendly. I even deleted her from my fb.

Lately though I have been thinking about her. Still feeling a lot of guilt over what happened a few years ago and I almost feel a second chance or something might make that feeling go away.

I was thinking of messaging her again... Should I? Should I walk away from it? And what should I say? I thought of asking if we could be friends again but that sounds desperate? If I shouldn't contact her, then how could a get away from the feelings of guilt? There is pretty much no one I feel comfortable talking about it with in person... Any advice?

Thanks in advance for any help!!