How Can I, A Soft Hearted Guy, Get Over A Girl Who Cares For Me And I Care For Her?

There is a girl/young woman who goes to my church back home. Mind you, she is 6 years older than me (she’s 24 and I’m 18). I randomly started talking to her online one day and we both thought the other person was really cool. So we talked more and more, and eventually when summer came, she said hey, let’s hang out. So we hung out whenever she wasn’t working. I started thinking to myself, man, I wish she was my age, because she’s a really cool girl.
One day though, after going to the pool with her, we came back to her parent’s house, and somehow things led to sex. So, I lost my virginity to her. She had told me online before when we were discussing our problems, that once she got to college she started making mistakes sexually. So.. i felt bad for just adding on to her list of mistakes. I felt horrible for having sex too though.
Anywayy.. after sex, as would be expected, I fell for her. HARD. I started considering her as a girlfriend, and wanted to date her pretty badly. Only one problem. I knew she was 6 years older than me, and plus, she goes to a different college than me.
I talked to a really cool pastor here in my college town and he told me that sex ties an invisible string around two people’s hearts, and that I share with Lillian (the girl’s name, which is freaking awesome name too) is an unhealthy one. He suggested that we take a season off from each other. Not communicating, and getting our hearts in the right place and our minds cleared.
See, I completely agree with him, and I want to do this, but it’s almost impossible for me to. He’s right it is an unhealthy connection. My heart tells me that I love her, but my mind says I’m retarded. She goes to clubs, wears sexually appealing clothes, and is really attractive and gets hit on by a lot of guys. It’s not something I usually look for in a girl, and some of it is a turn off.
She’s Christian and wants to do things that are right, but she is REALLY naive, and it bothers me. But, because she’s naive, and I care for her, it really hurts me that I can’t be with her to watch out for her, and set her straight. I always tell her things, and she’s like wow, I never thought about it that way, or wow, I didn’t know that. She’s very naive, and it makes me care for her even when I don’t want to.
What the heck do I do? I’m sitting her hurting day after day. I hung out with her all day this past labor day weekend, we both came home from college to visit. We made out, hugged each other, and I cried, she cried because I was crying. She tells me that she wishes she had a boyfriend like me, and that she would wait even longer than she has been waiting for someone like me. She’s a sweet, caring, lovely girl, who has an innocent heart, she really does. But just not so aware of the things she’s doing. I wish I could not like her or stop thinking about her, but I absolutely, positively can’t.
It’s gotten to the point that when I try to hang out with girls in college, I feel uncomfortable, because I feel that I’m somewhat committed to Lillian? wtf, right?
Please help me.. I have a really soft heart.