Along with everyone else, I offer my sympathies.
Ever heard the term "Love is blind"? If you read and re-read your OP, I think you may be able to identify at least 3, maybe 4 red flags in your relationship.
1. The fact that she told you over the phone is totally asinine. Who breaks up a 3 yr relationship over the phone? I fully agree with you on this point. And agree with Luvs2Squirt. This is characteristic of a selfish and insecure person.
2. You please her, but she would not completely please you...even after discussions. Selfishness, again. (Red flag... it's very difficult to maintain a "long term" when only one person is satisfied, even if you are going to your friend for services.) You communicated and you tried.
3. She dumped you for a guy that has once been humiliated and demoted at the job (to which he is returning). It's possible he's told her he has changed and she believes him, but she is more than likely in for more of the same. (Especially if she reciprocates sex with him as she did with you....) Just sayin'.... something to think about here.
4. Incompatibility comes in many forms. She may have felt that sexual incompatibility was enough to say this. OR there could have been other signs that you failed to see b/c you were in love with her. TONS of reasons to be incompatible, and lots of times, people do not argue. Some find arguing futile and useless, so they internalize and just go on as if all is ok until they explode. (I married one of those...and gladly we have worked through that.) What I'm saying is "Just because she says 'I'm fine' doesn't necessarily mean she is".
I'm not a therapist or anything, but I've seen relationships fall apart for far less than what you have indicated here.
Yes, you are hurt. You have a right to be hurt and angry. Address it, logically, now. (agree with umami.... no breaking, no drinking yourself silly..that is only hurting yourself) Be/do something constructive with your anger... like running, gardening, building (hammering nails is always good)
You will get over this.
Do not let this girl ruin you for the rest of the women. You have something good to offer the right person.
Good luck, mister... take one day at a time. And don't forget to breathe