How to be friends again

[frch25]

I have this girl at my workplace that I liked and she liked me too. There was a complication because she had already a boyfriend abroad. After a while we became such good friends that we became intimate and said we loved each other. I was really having a problem that she still was with that other guy and at times reacted jealous towards her. About two weeks ago her boyfriend came to see her for a vacation and she said she didn't want to turn her live upside down and just wanted to be friends with me. I was very upset and not nice to her and it was difficult because we work together and I was really angry. That evening I apologized and we went shopping as friends and I bought her a lot of expensive stuff that she accepted with no problem. But after the weekend at work I started to be very jealous and upset again and after that she didn't want to talk again. I want to be friends with her again and wrote her a letter but she said she won't talk to me for a while and seems really very angry with me. She stills wear the stuff I bought her. Is there any chance we can become friends again. Please help because this situation hurts like hell.