Hey there, guy:
I see you're 22. When I was 21, I spend a year studying up on all the things I needed to do in order to get women. When I went into my senior year in college, I thought I'd be able to ace this thing... lo and behold, though: I started going out with a girl - a friend of mine I had known for 3 years (so yes, people, it IS possible to date a friend IF you know what you're doing)... but I was so used to the version of myself that was BAD with women, that even when I was getting results to the contrary, a part of me was still saying "This girl can't REALLY want you like you want her to... if you make a move and it's the wrong one, you'll be SO humiliated..." As a result, I ended up losing that girl and got depressed about it for quite a few months - not just about her, but about still not having this whole "dating" thing down like I wanted.
What helped me get through it? Well, first I had to let my feelings hit rock bottom. It wasn't pretty either - days in bed, and I ended up slacking on my class work and actually failed out my first senior year in college. I don't recommend you going this route, lol...
After that, I decided to "get myself on paper." I went back and thought about every single mistake I ever made in my dating life with women, from saying the wrong thing, to not recognizing when a girl liked me, to when I did AFC stuff like writing poems and telling them I liked them too much... and I wrote all of this stuff down. Actually, I ended up making it into an eBook that teaches guys how to NOT do all the wrong things I did when trying to get girls. (Available at the link in my signature.)
Anyway... by doing that exercise, it gave me something to reference whenever I started feeling my old ways creep back up. For example, if I felt myself wanting to buy a girl a gift, I could look at the notes I wrote about how getting gifts for girls in the past didn't work, and it would remind me to NOT do that. Or, if I thought about calling a girl right after a date, I'd remember how doing that in the past resulted in a girl NOT wanting to date me anymore, and so I wouldn't do that action.
It also allowed me to remind myself that all of these scenarios started out with women who actually LIKED me at one point, or were, at the very least, open to giving me a chance. Even the girl I mentioned earlier - she was open to coming over to my apartment, watching a movie with me, feeling on her boobs... all that stuff, and yet I was the one who ended up messing up everything by not having confidence. But the point is, these girls gave me a SHOT. And if they were giving me a shot, it means, on a subconscious (or, in some cases, conscious) level, they had an attraction to me.
Lastly - and this is the hardest part for a recovering nice guy - I had to realize that I was not responsible for their feelings. Much like you, I worried about getting with a girl, realizing I didn't like her, and then having to hurt her feelings by breaking up with her. The reason I felt that way was because I wanted to be able to control the feelings she would have should those things happen, i.e. if we broke up I didn't want to see her cry, I wanted her to still view me as a "good guy," etc... over time, though, I realized that I couldn't control what her reaction was. All I could do was be the guy I was and, should those moments arise, know that I would do the best I could to handle them as best I could without malice. Now, if I tried to let her down gently during a break-up and she starts going postal, her reaction has to do with how she was raised to handle things when they're not going her way - it has nothing at all to do with you, other than you giving her a blow to her ego when you say you're not interested anymore.
So, that's what I can offer you as suggestions. Oh, and check out the link in my signature - I have a podcast with over 260 episodes (all free) that you can listen to in order to start changing your mindset about dating. Hope this helps!