Didn't read whole thread, and this has probably already been said, but you're already in the early stages of breaking up. Whether its a conscious decision or not, women start making the moves long before the final decision is made. Not putting out is step number one. I know it sounds chauvinistic, but its true... when the sex dries up, its a major warning sign (assuming you're both young and healthy). Her being short-tempered and insensitive to your needs and feelings is another sign. Sure, this is bound to happen from time to time, but if its consistent, or if its a change from previous patterns, you're in trouble. I think some women need to go through the process of fuxoring up a relationship before hand just to make it easier to break up. :hs:

If you think there's a chance, you gotta come clean. Don't just suck it up and endure it. Have the conversation now. Tell her you care for her, but she's treating this relationship like garbage, and you wont stand for it. If she shapes up, great, but I don't see a lot of promise here.