So I've been seeing this girl I work with?

for almost a year now. We have always been discreet about our relationship, especially at work. Well I've just found out she's been seeing a fellow co-worker for the same amount of time. I feel horrible that I was played so easily, but the worst part is that after we both confronted this girl she only apologized to him and only told him that when she said she loved him she meant it. She has ignored me ever since. I'm losing sleep and getting sick over this. How can I get over it? I rarely see her at work, so I don't think I'll have to find a new job.