I'm in a bad situation..how to deal with it?

To make a long story short I found out about two hours ago that my boyfriend of over two years has been sleeping with my three friends for the past two months. I've always been shy and never had many friends..these were my only friends. The truth came out tonight when he admitted that was he hanging out with them behind my back and that he wanted to show me "what bad friends they are." In retaliation they told me all about the they been having with him. How stupid could he be to not think they were going to get him back by telling me everything. He even had with one on Superbowl Sunday. I know this is all the truth because everything falls into place and I had suspected he was messing around on me but I had no proof. My body is numb and I don't know how to deal with all this. I live with my mom and stepdad and told them what happened and they are trying their best to be by my side but I am still in a lot of pain and shock. The thing is..one of the "friends" works with me at a retail store (I got her the job when she lost hers) and I have to work with her almost everyday. I want to tell my boss to change my schedule so I don't have to work with her. I feel as if my temper will get the best of me if she is near me. Now I have no friends or boyfriend and I am feeling very depressed and alone. I was recently diagnosed with depression and this is just another setback. My question is how do I move on with my life and get over this crisis..and also what to do about my job situation since I have to work with the sl*t. Any advice is appreciated. Sorry for any typos I'm just very upset and shaky right now.