Should I tell him how I feel?

I’ve had a thing for this guy in my class at college for a year, but don’t think I am good enough for him because I have seen the kind of people he goes on dates with. I am worried about embarrassing myself by saying something to him, because he may brush me off and I know that will hurt me a lot. We barely chat in class, and I have no idea if he has even looked at me seriously, but I can’t get him out of my mind. I keep telling myself that I will regret not telling him how I feel, which is why I want to say something before the semester ends. Is this going to end badly for me? Should I just drop the whole idea and save myself unnecessary pain?
If you feel strongly about someone and want to say something, you should, irrespective of what you believe the outcome will be. You acknowledge that you don’t know this person well and have no idea how he may react, but why assume the worst scenario? Yes, it’s always possible that he may have no interest in you at all, but that is his prerogative and it’s perfectly normal for people to have perspectives about whom they like to date. Why not start by having a conversation, and give him an opportunity to get to know you better first? It is only by 
building this acquaintance that you can ask him out for a cup of coffee and see what happens. You don’t have to discuss your feelings when there are other things you need to be able to speak about first.

My boyfriend and I are both guilty of not being faithful to each other over the three years we have been together. Should I assume this relationship isn’t meant to last?
That depends upon how you feel about each other, what you both want from this relationship, and how much work you are willing to put in to make it work.