Should I leave a partner I lived with for 3 years who loves me and stay on my own hoping to be with another?

I am with this guy (I will call him American Guy) since 2006 and after some dating, I decided to move from Italy to the US to live with him at the end of 2006. Now I am allowed to be in the US because I am an international student at the college and I just got into junior classes.

These are the problems:

1) We barely have sex since the first time we have been together.

2) I cannot work because I am an international student, and I'm paying tuition thanks to my parents money. I use my partner's car and he pays for rent.

3) I promised him I would take care of him as soon as I will be done with my CPA certification by approximately the end of 2011

4) He loves me to death even though we don't have sex. He plans for a future move to Europe where we would buy a Bed and Breakfast using my parent's money. He doesn't have much money, but that's what I like about him because I want to build something that can last a lifetime with someone.

5) I am not sure whether I love him. I met him as soon as I was left by a Polish guy. I tried to do anything in order to find a job and a house for Polish Guy in Italy, but since he did not speak Italian very well, he never really found a job. He only wanted to be a hotel receptionist though. Me and American Guy talked on the phone for 7 months until he made me go through my heartbreak. The problem is that I only went through my heartbreak one year ago (which is two years after we dated), waking up one day and finding myself in American Guy's home.

6) Now there is another guy (Texan Guy). He's the most wonderful person in the world, and I cheated on American Guy with him. I know it's very sad, but it just happened. He wrote "I am not sure where things are headed! But I can tell you that either way I would like for you to be a part of my life." He means either as a friend or a boyfriend. He seriously messed with my mind. I can't stop thinking of Texan Guy, and he's making me feel alive all over again. I have never felt like this with American Guy. But I know that if I leave American Guy, I will have to start buying my own car and pay for rent. I also keep thinking that American Guy loves me to death and I don't want to hurt him. I don't think he deserves such a treatment from me.

Should I keep staying with American Guy or Texan Guy? In other Words, should I think for myself or for American Guy's goodness?