> To me, it was like one day she loves me, the next she tells me she doesn't love me anymore.

She picked the other guy over you, then broke up with you to be with him. Chances are she was doing him behind your back. Of course she didn't tell you that she was attracted to someone else beforehand.

> I do too, even if only in the hopes she comes back to me someday

After this? Move on, man. Whether you move out is a different matter.

There's a simple cure for your kind of problem: find someone else, even if it's a fling. It's not like it's hard if you go to the usual places.