What to do when i feel humiliated and bad?

i found this cute cellphone pouch in our cafe where i work and used it for awhile while the owner is not looking for it yet. But then a friend came up to me and said it looked exactly the same of his friend's cell pouch . He asked me where i bought it and how much? i was dumbfounded. i felt so ashamed of myself. I was happy when i found it hoping the owner will not look for it anymore but with what happened i realized it was not mine after all and it made me feel stupid for using somebody's stuff not mine. i don't wanna use it anymore. it's a big deal for me bec. i just went to confession and i feel such a big fat liar and thief. Any encouraging words for me? thnx